What is 300 dpi in photography. How to set photo resolution

12:36 pm - FAQ | What resolution should I set for the photo?

So, today's question that I get asked regularly when it comes to saving processed photos to disk:

#16 What resolution should I set for the photo?

We're talking about mysterious dpi, which are often appropriately and inappropriately mentioned by customers in technical requirements to the photographs. But you won’t find something like this everywhere - more often you come across it in program interfaces ppi and no dpi. And customers write and write "send us a photo no less 300dpi!" What is all this and why do photographers need it?

Short version:

In short, this is the density of location:

And, what’s most interesting, all these things have nothing to do with raster digital photography until you are about to print it! That is, if you don’t print your photographs (and now there are more such photographers than those who print), then you don’t have to bother yourself with these parameters at all, you won’t need them.

But, just in case, you can set the resolution box to 300. In Lr, for example, this can be done when exporting images, here:

For everyone else, there is a detailed answer. =:)

Expanded answer:

A digital photograph on a computer has only one size characteristic - the number of vertical and horizontal pixels (or their product, now calculated in megapixels). Here is this card, for example:

Has a size of 900 x 600 pixels (or 540,000 pixels, which is equal to 0.54 megapixels). The original frame from which this smaller copy was made was 3600 x 2400 pixels (or 8.64 megapixels). And these values in pixels are the only parameter responsible for the size of photographs in digital form.

Problems may arise when you want to print a photo. Different printing machines and printers, depending on their design and the purpose of the print result, allow you to create images with different pixel sizes. That is, you can print large pixels and then only a few of them will fit on one inch (about 2.5 cm):

Or you can reproduce pixels of a slightly smaller size and then more of them will fit on one inch:

Or you can make them tiny and then there will be a lot of them on the same linear inch:

As a result, if the same image is taken and printed with different pixel densities per inch ( ppi), then it will have a different size on paper:

It is believed that when more than 300 pixels fit on one linear inch, the human eye is no longer able to separate them, and this gives high-quality, “smooth” printing, without noticeable pixelation. The vast majority of glossy magazines use exactly this (or so) print density, and you can see the result for yourself by purchasing “glossy” printing at any kiosk.

In fact, now the density of 300 ppi is considered a kind of unspoken standard that most publishers focus on. Although, as far as I know, this particular figure does not appear anywhere in the official standards. Well, let me be corrected if I'm wrong.

At the same time, if we are talking about printing, for example, outdoor advertising posters (billboards) of a large size (3 x 6 meters, for example), then there is no such need to make the pixels microscopic and print them close to each other - viewers will still look at the poster look at it from a fair distance, not like looking at a magazine. Therefore, very often when printing materials for such billboards, a resolution of about 50 ppi is used (there are 50 image pixels per inch of a printed poster).

Ideally, you should know what print density you need and prepare your photos accordingly. If we talk about Ps, then this can be done in the menu item Image -> Image Size:

At the top of this palette we can see the photo size in pixels (3600 x 2400):

And at the bottom - the size in centimeters (127 x 85 cm) with a density of 72 pixels per inch.

These 72 pixels per inch now, in general, look like some kind of spherical horse in a vacuum, because this is a purely rare indicator that is now traditionally assigned to all digital images by default. And it has no real implementation, because someone is now looking at an image on a 15" diagonal monitor with a resolution of 1024 x 768 pixels and it will have the same image density, and someone can look at a 25" monitor with 2560 x 1600 and its density will be different. But it is so traditionally accepted that digital photos are assigned exactly this figure - 72 ppi. "The answer to the ultimate question of life, the universe and everything is 42!"

By the way, it was not for nothing that Apple engineers described in such detail the advantages of the iPhone4 screens when they first appeared on the market. With a diagonal of 3.5 inches, the image dimensions are 960 x 640 pixels, which gives a resolution of 326 ppi. Which, as you understand, is quite comparable to the quality of good printed printing. And in the future, I am sure that the number of devices with high ppi will grow steadily.

If you uncheck this box:

Then you can see how the image size changes depending on the ppi density (and with the same image size in pixels - 3600 x 2400). At a density of 5 ppi (each pixel will be printed as a 5 x 5 mm square), the image size will be 1829 x 1219 cm:

With a “magazine” density of 300 ppi, the size will already be 30 x 20 cm (almost A4 format, that is, the cover, for example):

At 600 ppi, the photo will take up 15 x 10 on paper (“photo, 10 by 15 with a naive caption...”):

And at 10,000 ppi, the size of this photo will be less than one centimeter on its larger side:

It is clear that printing with a resolution of 10,000 ppi generally makes no sense, especially considering that the threshold at which pixels are visible is considered to be a resolution of 300 ppi.

If you still want to display an image with a resolution of 300 ppi, but on a larger medium, then you will need to turn the checkboxes back on and change the image size in centimeters:

At the same time, please note that the image size in pixels will also increase. This is inevitable, because you want to leave the print density high and you want the size to be larger, which means there will be more pixels in the image. Ps will add the missing pixels, calculating them from neighboring ones. The image quality may suffer noticeably.

Well, what then is it? dpi, which customers love to write about in their image quality requirements? This is the density of dots printed by the output device. And this parameter is purely technical; it can tell a specialist how many dots, for example, a particular printer can print on one inch of an image.

Strictly speaking, dpi not always equal ppi. After all, one pixel of an image must be transmitted by several points on the printing device:

Here we can see that each square (digital image pixel) is represented by several circles different diameters. Due to their different sizes, it is possible to create different color densities, and, as a result, to obtain full-color images with halftones on print. But the printing machine cannot make dots of different sizes; it can only create spots of a certain diameter included in the design. Therefore, the circles we see actually consist of many small dots:

The density of these dots per inch is the parameter, which is denoted as dpi. And if you count, then ppi of this example will be, say, equal to 25, then dpi will be many times more.

But in modern practice, it has already developed that in the requirements for the quality of photography, they very often put an equal sign between ppi And dpi. And they come as a result of demands, like "the final image should be 6 x 3 meters in size at 50 dpi", which translated into digital image language means that the picture should be 11811 x 5905 pixels in size. Just like you come across demands like "the image must be at least 3600 x 2400 at 300 dpi", which, as you now understand, does not even look like “oil oil”, but like “square oil”. =:)

"Give me back my money!" This is how a stock photo client started the conversation, who bought a photo for advertising on a billboard, but it turned out that it could be printed on a mug at most. She didn't get her money back, and here's why.

When you buy a photo on stock, it seems that the main thing is to find a good frame, and the rest is unimportant. But then there is the question of choosing a license and image size, and this is where the fun begins.

Buyers of stock photos are not always experienced designers or build editors. And ordinary person the terms “resolution” and “dpi” inevitably raise questions, which the “Help” section on the photo bank is intended to answer. But not everyone likes to read it, preferring to trust advice from a search engine or their own intuition. So such troubles happen as “Oh, I downloaded the wrong size” or “Why did the photo print so poorly”? Unfortunately, the photo bank cannot exchange a purchased photo or return money - stock content cannot be exchanged or returned.

To answer all these questions once and for all, we've put together a list of tips for stock photo buyers. It clearly and to the point says what you need to pay attention to when purchasing stock photography.

Size matters

Photo banks, like any other online stores, strive to adapt to customer needs and offer different types goods. One needs high-resolution photographs for printing in a magazine, the other needs a small picture to illustrate news on a website. Moreover, if the first one “plays for high stakes” and is ready to pay several thousand for one photo, the second one will not be delighted with such a price, because his needs are not comparable with the costs.

This is how the division of photographs into sizes appeared. Different photo banks have different designations for image size - in some places it’s just the image resolution in pixels, in others it’s a letter designation, and often different photo banks have the same ones letter designations do not match. The photo bank has these letters, like in clothes:

XS - 400×300
S - 800×600
M - 1600×1200
L - 2560×1920
XL - 4200×2800
XXL - 4700×3400

These values should not be taken as an ironclad rule. The exact size of a photo depends on its orientation (portrait or landscape) and the aspect ratio, so two photographs of, say, M size may differ in pixel resolution, albeit slightly.

Despite the fact that photo banks offer a wide range of sizes, it is better not to save money and buy images of at least 1600x1200 pixels, even if you plan to use it only on the web, and maximum size, if you want to print it on a banner, poster or magazine. We recommend doing this not out of thirst for profit, but based on experience in working with clients. Read more about choosing a size in this article.

Forget about DPI

When it comes to printing, the concept of DPI (from English dots per inch) appears - a numerical expression of the resolution of a raster image. This resolution determines how detailed the image will be when printed.

The main thing you need to know about DPI is that it is a relative value that can be set independently in almost any graphics editor, and it is only needed by the printer, which learns from it how many dots of paint (pixels) to make per inch (or centimeter) when printing. All.

Many printing houses require images to be printed at 300 dpi, which is considered the standard in modern high-quality printing. If you print an image that is 6900x4500 in pixels at 300 dpi, then in centimeters it will be approximately 58.5x38.1. That is, in 1 square inch of the image you will place 300 dots (aka pixels). In this case, the detail and clarity of the image will be very high, as in glossy magazines.

If you look at a photo in a magazine.

If you look at the photo in outdoor advertising.

Even if you have eagle vision and view the printed image from a few centimeters away, you most likely won't notice any dots.

How it's done?

In order to find out the size in centimeters, you need to do the following: take the length or width in pixels, divide this value by the number of DPI with which you plan to print. The resulting value in inches must be multiplied by 2.54 (there are 2.54 cm in one inch). 6900 px / 300 dpi = 23 inches * 2.54 cm = 58.42 cm 4500 px / 300 dpi = 15 inches * 2.54 cm = 38.1 cm

Many people immediately have a question: does this mean that an image that has a resolution of 6900x4500 pixels and a parameter of 300 dpi cannot be printed in a size larger than 58.5x38.1 cm?

We answer: no, it doesn’t mean that. Nor does it mean that this image cannot be printed in a size smaller than 58.5x38.1 cm.

If you stretch the picture to a larger format, then there will be fewer dots (pixels) in one inch than 300. This does not affect the perception of the picture in any way, given that as the image size increases, the distance from the eyes to it also increases. It is convenient to view a magazine at a distance of 30-50 cm, and a huge billboard can be viewed from a distance of several meters, if not tens. From there, you won’t be able to see individual dots/pixels, even with binoculars.

Different needs require different dpi settings. For a black and white newspaper, for example, 50-70 dpi is quite enough; for a full-color offset in a book, approximately 120-150 is required, and for a billboard on the street - only 6-10. The peculiarities of the observer’s perception of images are very important here - the larger the picture, the greater the distance a person can comfortably perceive it. 36 dpi is the resolution at which a person cannot distinguish the dots (pixels) in the image from a distance of 1-2 meters.

How to choose a license

After technical characteristics, choosing a license does not seem so difficult, but there are pitfalls here too. For example, the standard Royalty-Free license, under which most microstocks operate, does not allow the purchased image to be used on the street, even if it is just a billboard or poster. All outdoor advertising is subject to an extended license, which is several times more expensive than a standard one.

In an effort to save money, or out of ignorance, people can buy a photo under a standard license and place it on, say, a huge advertising billboard. If someone doesn’t like this advertisement (citizens of the Russian Federation can freely write complaints about advertising, and the prosecutor’s office is obliged to sort out such applications), or this billboard catches the eye of the author of the photo (authors like to see where and how their work is used), then there is a great risk go to trial and pay the author a fine of 10,000 to 5 million rubles for violating the terms of the license. Therefore, it is better not to take risks.

We described in some detail which license is suitable for a particular case. Take 3 minutes, read it, or contact our support specialists, who are always ready to help.

You don't need to be a genius to understand these simple terms and licensing features. Can they cope with smartphones and use a computer, after all? We are sure that this material will not reveal anything new to you, our readers, but if we managed to remind you of something or clarify some unclear points, that’s good!

DPI is an abbreviation for English. dots per inch(dots per inch) is a numerical expression of the resolution of a raster image. Resolution determines how detailed your image will be when printed.

So - the photograph does not and cannot have any DPI! If only because it does not have a fraction denominator, there are no inches. While the photo lives on your computer, is viewed on the monitor, walks around e-mail, there is simply no need to talk about any dpi. The parameter becomes meaningful only at the moment of printing. A photograph has only absolute resolution—the number of pixels vertically and horizontally. Let's say, if a photograph was taken by a camera with a 6 megapixel matrix, then its absolute resolution will be 3000 x 2000 pixels. This is all!

Can this image be printed at 300 DPI? Yes, of course. What size will the print be? 25.4 cm * 16.9 cm.

If this happens in life, I personally have never encountered it. In any case, the dimensions and proportions of your photo in the magazine will be different. When printing the same photo with different sizes, the resolution will also be different, and in any case it will not be equal to 300 dpi. Not to mention that most often the layout designer crops the image in accordance with his ideas, technical specifications and general concept. Let us repeat once again: as long as there is no printing, there is not and cannot be any DPI.

The dpi value only makes sense at the moment of printing:

300 dpi- This technical requirement for permit illustrations in modern high-quality printing. The printing house makes it clear to you that in order for your cover to be printed perfectly, this is exactly the permission required. Knowing the requirements for printing resolution and the size of the print, you can independently estimate how many vertical and horizontal dots the source image should have.

* — By the way, the number “300” itself is also very arbitrary here. It’s very easy to dispel doubts - imagine a poster with dimensions of 1 x 1.5 meters. With the resolution of 300 dpi required by the would-be designer, the source file should have a resolution of 11800 x 17720 pixels, i.e. approximately 210 megapixels! Even the most modern professional photographic equipment has not yet even come close to this value. And the posters hung and still hang.

For a b/w newspaper, for example, 50-70 dpi is sufficient; for a full-color offset in a book, approximately 120-150 is required, and for an outdoor billboard - only 6-10. Here everything is determined by the characteristics of the observer’s perception of the image - the larger the picture, the greater the distance a person can comfortably perceive it. The postage stamp is brought to the eyes, the magazine is held in the hands, and they move ten meters away from Bryullov’s canvas. One thing remains unchanged - the angular resolution limit of the eye (about 1 arc minute). This is what professionals rely on when calculating the required resolution.

What permission is required in practice? In a general sense, the more the better. If we are not dealing with unusual areas of professional photography (aerial photography, photographic recording of scientific processes, photo wallpaper), then in the vast majority of cases we can get by with an absolute resolution of 6-10 megapixels. Why is the “de-peh-i” misconception so widespread? Because people rarely think about it.

Is it simple? Yes, sure. It took you and me three minutes to get the point. Therefore, if you hear the phrase “give me pictures with 300 dpi” from a designer (layout designer), run away from him, you are dealing with dense laziness. And laziness, sooner or later, will ruin any business.

P.S.:
What does the value specified in the file properties mean (72, 150, 300 dpi)? This is only the recommended resolution when printing a photo in fully automatic mode, indicating to the printer a lazy owner. And this value can be painlessly changed to any positive integer. Nothing will change in the photograph itself.

P.P.S.:
Do you still require “300 dpi”? They say that the best way to teach psychology is at a geisha school: “if they ask you for a drink, don’t be stubborn like a donkey, take a sip and put the glass on the table.” Make it 300 dpi. Or just provide a link to this article.

Photography in St. Petersburg. +7 921 337-24-39. Photographers Service. Professional photography of corporate events, holidays, conferences and seminars. Industrial and advertising photography, photographer for corporate events. Cooperation with city media and PR departments. Interior, subject, reportage, event photography. Experienced photographer, photojournalist. Professional processing and photo printing. Photo reports to order, photography for catalogues, booklets, calendars. Business portrait, photography for corporate honor boards. Virtual spherical panoramas, virtual tours. Photo services, development and compilation of a photo bank.

www.nevaphoto.com

Resolution 300 dpi - how does this compare with photo sizes of 2400x1600?

DPI is an abbreviation for Dots Per Inch and stands for Dots Per Inch.

DPI = 1PPI (pixels per inch).

An inch is a unit of length equal to 2.541 cm.

Pixel - “picture element” - is a point (minimum particle) of a digital image. Everything you see on your monitor screen or digital camera display is made up of pixels.

When we talk about digital image resolution or digital image size, we mean the number of pixels along the length and height of the image. As a rule, the more pixels an image contains, the larger and better quality it can be printed on a printer or displayed on a monitor.

DPI matters if you need to print an image of a certain size. Let's say, if you need to print a 10x10 cm image with a resolution of 300 DPI, then divide 10 cm by 2.54 (1 inch = 2.54 cm) to get a 3.9 x 3.9 inch photograph. Now we need to multiply 3.9 by 300 DPI and we get the photo size in pixels of 1050 x 1050.

This is how slide scanners and digital cameras measure input resolution - in terms of the total number of pixels that the cameras' CCD matrices (for example, 1280x960 on the AGFA ePhoto 1680) and the scanner's optical systems are capable of inputting horizontally and vertically.

The image resolution is directly related to the resolution of the digital camera matrix. 1, 2, 5 MP (megapixels) is the resolution of the digital camera matrix. That is, the number of minimum image elements (pixels) that it is able to capture.

The higher the resolution, the sharper, richer and simply better quality the image is.

300 dpi, according to Russian standards, is 118.11 pixels per centimeter.

There is a resolution in dpi and there is a photo resolution in pixels in width and height, which means we can calculate what size photo this will be enough for without losing quality.

Because any photo can be stretched (stretched to required sizes) and roughly see whether the squares have begun to protrude or whether it is tolerable or will go in the squares.

Even if the photo needs to be made narrower or wider, you can crop the top or side edges and slightly re-center the photo and get what we wanted.

The size 2400x1600 has a standard, this is 96 dpi, this is the windows standard known as the monitor standard, since you have a photo, then it was taken by the camera in this resolution, because when creating photos or even in graphic editors, the 96 dpi standard is used, probably only by -by default, excluding Photoshop, it offers either 72 or 78 dpi which are easy to fix.

96 dpi is 37.8 pixels per centimeter in Russian.

And now we adjust it to the centimeters, use the real dpi of the photo, with new knowledge it is 96 dpi, which means that there will be enough of them for the photo:

63.50 cm - wide
42.33 cm - height.

if held in hands horizontally, if vertically then

42.33 cm - height
63.50 cm - wide

And you ask to print it in 300 dpi resolution, this means this photo is enough for sizes of 300 dpi, that’s what

20.32 cm - wide
13.55 cm - height

At 96 dpi, when you approach your eye you will see a grid and space between them
At 200 dpi the eye can no longer see anything
Even more so at 300 dpi

There is no point in having a resolution in pixels greater than the dpi allows, it will simply squeeze them to the maximum resolution allowed under the printer resolution, for example, as you indicated, 300 dpi. This is a huge picture, 2400x1600 is already a lot. 2400x1600 is so that the squares in the image are not visible, and 300 dpi is so that the pixel grid is not visible.

21260 pixels wide. How many cm in height? Only this is a square, if you need to print on the fabric, but it is not square (the width and height are not the same), then it is not known how at will This will be done by the printer, or by a program that drives the image into the printer, or by all of them. Measurement of the area where to print the width has already been done; this leaves 180 cm in height. Possible options if you insert a square, there will be either trimming or stretching (in the photos when the faces are stretched wide or high) if you don’t know.

What is 300dpi resolution?* And how many megagrams should a photo weigh to achieve such a resolution?

First of all, what is dpi? dpi (pronounced dipiay) is an abbreviation for English. dots per inch dots per inch. Used to indicate resolution when entering or outputting information from/to flat media. It is measured by the number of points per inch of surface. For example, the designation 600 by 300 dpi for a printer means that its resolution is 600 dots horizontally and 300 dots vertically per 1 inch.
How high should the print resolution be so that the eye does not distinguish individual pixels and perceives the image as high-quality?
72 ppi Standard resolution for computer monitors or prints viewed from afar (for example, posters) At close range, the pixels are noticeable.
150 ppi High enough resolution so that the eye does not notice individual pixels and perceives the picture as a whole.
300 ppi Photographic print quality. A further increase in resolution is only necessary if the print is viewed through a magnifying glass.
All this and more related to digital image printing can be found here:
http://photo-restoration.narod.ru/page16.html

Here are some useful tables for you:

(see http://www.olympus.com.ru/consumer/208_741.htm)

dpi - Dot Per Inch

that is, dots per inch. How much a photo will weigh depends on the size of the photo - for example 1024*768 or whatever size you have

There is no clear relationship between relative resolution and file weight.

It depends on what format (in centimeters or inches) we are talking about. Based on this, you can calculate how many dots on each side a file should have in order to be output at a resolution of 300dpi.

And the weight of this file will depend on the format in which we save it.

300dpi – myths and reality. How much do you really need?

Frequently asked questions on this topic: less or more dpi? The more the better quality photos? And how does this relate to the size of the photo itself?
More and more often there is a misconception about the “quality” of images and the required 300dpi.

First, let's define what dpi is... Dpi- This is a parameter indicating the resolution of the image per inch when it is printed. And here the attentive reader will think. Yes, yes, precisely when printing. And as long as you don’t print the image, but just look at it on the monitor and process it in Photoshop, dpi doesn’t matter at all. It does not affect the quality, nor what size you will print the photo (10*15 or A4) and does not affect anything at all. The only one important parameter while your photo is digital, this is the size in pixels. That's all! This is the harsh reality.

Let's take it in order:

1. What if less or more than 300?
Yes, you can as much as you like. As long as you don’t print, there is no difference, even 1dpi, even 1000dpi.

2. What about quality? After all, at 300 everything will be fine, that’s what they write everywhere on the Internet and in general it’s what everyone hears. Does this mean that if the value is smaller, the quality is worse?
As I wrote above, quality has nothing to do with the dpi parameter. Dot. Deal with it.

3. But what if I'm going to print a photo? Then this parameter is already important and the more the better?
Not really. This setting specifies how many dots (read: pixels) will be printed per inch of the image. In this case, you can set any dpi value. For example, there is a photo measuring 4000*6000 pixels. At 300dpi it can be printed at 34 cm * 51 cm (rounded to tenths). But you can also print with a different dpi value. At 150dpi it will be 67.7 cm * 101.6 cm.

4. What value should I set then?
It depends on where the printing goes. If it's for a glossy magazine, then 300dpi is quite suitable. For home in Family album– 100-300dpi (approximately). And for a huge billboard, 20-70dpi is generally enough.
But I repeat once again - the size in pixels is more important if we're talking about about quality! Imagine that you have 2 photos on your computer: One is 600*800 pixels with 600dpi. And the second is 2000*3000 pixels with 70dpi. Which of them can be printed more and with better quality? It would seem that the first one, it has as much as 600dpi - cool, that means it! But no, physical size the second file has more pixels, despite the measly 70dpi. The dpi parameter itself, while it is in a digital file, does not mean anything. When printing these two files, you can already select the required dpi value. We will average it to an adequate value of 250 (here we could take any number) and get a physical print of the first file 6.1 cm * 8.1 cm, and the second 20.3 cm * 30.5 cm. As you can see, who has a size of more pixels - the physical size when printed is larger.

5. Where does 300dpi come from then and why is it required almost everywhere?
I don’t know where exactly the number 300 came from, but with this value, the printing house or photo lab guarantees you excellent print quality (taking into account that the pixel size also corresponds). Essentially, this is an average figure that may vary depending on your printing needs.

In this photo, 2 photos are opened in Photoshop. The photo on the left is 900dpi. The photo on the right has 1 dpi. As you can see, physically they look exactly the same.

If you suddenly come across a person who calls himself a professional and demands some ridiculous 300 dpi from you, without understanding what they mean, this is an ignoramus with whom you should not work. A person cannot be a professional if he needs some parameters that he himself does not understand anything about. It is better to refuse the services of such a person. Be it a retoucher, photographer, illustrator or anyone else.

And now some lyrics. I've been meaning to write this article for a long time, but I kept putting it off. And lately I’ve been explaining to people more and more often that dpi in digital photography means nothing. It's boiling.

From real cases:
1 – The customer writes to me. Initially there was a scan of the photograph. And at the output you need, I quote: “You need a quality of about 600dpi, i.e. digital photo, not an edited scan...”
2 – In one retouchers public there was a conversation about how much dpi to set when retouching... And here is a quote from one retoucher: “They somehow wanted to force me to redo it, because it was 240.”
3 – We need a photo session, 10 output photos at 300dpi.

I hope you also appreciate the absurdity of these cases. and that's just for the last week.

sergbrezhnev.livejournal.com

How much is 300 dpi resolution?

I continue the section “Frequently Asked Questions | ( FAQ)". Traditionally, the questions themselves can be asked in the comments or sent by email:

So, today's question that I get asked regularly when it comes to saving processed photos to disk:

#16 What resolution should I set for the photo?

We're talking about mysterious dpi, which are often appropriately and inappropriately mentioned by customers in the technical requirements for photographs. But you won’t find something like this everywhere - more often you come across it in program interfaces ppi and no dpi. And customers write and write “send us a photo no less 300dpi!» What is all this and why do photographers need it?

In short, this is the density of location:

dpi (d ot p er i nch) - dots per inch

ppi (p ixels p er i nch) - pixels per inch
And, what's most interesting, all these things have nothing to do with raster digital photography until you are going to print it! That is, if you don’t print your photographs (and now there are more such photographers than those who print), then you don’t have to bother yourself with these parameters at all, you won’t need them.

But, just in case, you can set the resolution box to 300. In Lr, for example, this can be done when exporting images, here:

For everyone else, there is a detailed answer. =:)

Expanded answer:

A digital photograph on a computer has only one size characteristic - the number of vertical and horizontal pixels (or their product, now calculated in megapixels). Here is this card, for example:

Or you can reproduce pixels of a slightly smaller size and then more of them will fit on one inch:

Or you can make them tiny and then there will be a lot of them on the same linear inch:

As a result, if the same image is taken and printed with different pixel densities per inch ( ppi), then it will have a different size on paper:

Ideally, you should know what print density you need and prepare your photos accordingly. If we talk about Ps, then this can be done in the menu item Image -> Image Size:

At the top of this palette we can see the photo size in pixels (3600 x 2400):

And at the bottom - the size in centimeters (127 x 85 cm) with a density of 72 pixels per inch.

These 72 pixels per inch now, in general, look like some kind of spherical horse in a vacuum, because this is a purely rare indicator that is now traditionally assigned to all digital images by default. And it has no real implementation, because someone is now looking at an image on a 15″ diagonal monitor with a resolution of 1024 x 768 pixels and it will have the same image density, and someone can look at a 25″ monitor with 2560 x 1600 and its density will be different. But it is so traditionally accepted that digital photos are assigned exactly this figure - 72 ppi. “The answer to the main question of life, the universe and everything is 42!”

If you uncheck this box:

With a “magazine” density of 300 ppi, the size will already be 30 x 20 cm (almost A4 format, that is, the cover, for example):

At 600 ppi, the photo will take up 15 x 10 on paper (“photo, 10 by 15 with a naive caption.”):

And at 10,000 ppi, the size of this photo will be less than one centimeter on its larger side:

It is clear that printing with a resolution of 10,000 ppi generally makes no sense, especially considering that the threshold at which pixels are visible is considered to be a resolution of 300 ppi.

If you still want to display an image with a resolution of 300 ppi, but on a larger medium, then you will need to turn the checkboxes back on and change the image size in centimeters:

Strictly speaking, dpi not always equal ppi. After all, one pixel of an image must be transmitted by several points on the printing device:

Here we can see that each square (digital image pixel) is represented by several circles of different diameters. Due to their different sizes, it is possible to create different color densities, and, as a result, to obtain full-color images with halftones on print. But the printing machine cannot make dots of different sizes; it can only create spots of a certain diameter included in the design. Therefore, the circles we see actually consist of many small dots:

The density of these dots per inch is the parameter, which is denoted as dpi. And if you count, then ppi of this example will be, say, equal to 25, then dpi will be many times more.

But in modern practice, it has already developed that in the requirements for the quality of photography, they very often put an equal sign between ppi And dpi. And they come as a result of demands, like “the final image should be 6 x 3 meters in size at 50 dpi”, which translated into digital image language means that the picture should be 11811 x 5905 pixels in size. Just like you come across demands like “the image must be at least 3600 x 2400 at 300 dpi”, which, as you now understand, does not even look like “oil oil”, but like “square oil”. =:)

At least three parameters are used to measure the size of photographs - digital image resolution (in pixels), print size (in centimeters) and print resolution (dpi - dots per inch). A user who is first faced with the task of converting an image and preparing it for printing sometimes finds it difficult to understand these settings; he has to act at random and go to the desired result through trial and error, wasting a lot of time and paper.

Let's give a simple example of a problem. You need to take a photograph for documents. You can go two ways - go to a photo studio and take a photo there, paying 150 rubles for 4 small photographs printed on a sheet of 10*15 cm. The second option is to take a photo at home, prepare an A4 sheet for printing, on which to squeeze as many of your photos different sizes, which will be enough for several years to come. Then you go to a photo studio and print your creation on A4 sheet for 30 rubles. It seems that the profit from one order is ridiculous, but if you need to print photos for several people at once (for example, when the whole family is photographed for a visa before traveling to another country), then you can save a more significant amount. And this is just one example. Another question is how to maintain the dimensions of the photographs so that on the print they are exactly 4*5 cm (or some other size). In order to adjust the print size to the required size, you need to understand the connection centimeters, pixels And dpi.

Pixels

A pixel is one point that makes up an image. A pixel is also a cell of an image on a monitor or LCD TV. Examine the monitor close up and you will see a barely noticeable grid; one cell of this grid is a pixel. The photo that you downloaded from the camera has a resolution of several megapixels, that is, for example, 6000 pixels wide and 4000 pixels high - that’s 6,000 * 4,000 = 24,000,000 pixels or 24 megapixels. When viewed on a monitor, the image is automatically scaled to the monitor resolution (about 2 megapixels). If we try to increase the scale (we stretch the photo), then to some extent the picture is stretched without any visible loss of quality, but then characteristic squares appear on it. This happens when the actual resolution of the photo is less than what we want to see - the pixel size in the photo has become larger size pixels on the monitor.

Centimeters

I think there is no need to explain what a “centimeter” is. In our case, the size of photograph prints is measured in centimeters. Usually photographs are printed in sizes 10*15 cm, but sometimes larger formats are used - 20*30 cm (roughly equivalent to A4), 30*45 cm (A3) and larger. You've probably encountered a problem - you found it on some website beautiful photo and decided to print it in a large format (for example, 20*30 cm), but after printing it, we noticed that the quality of the print was not very good - the backdrops of the objects turned out to be a little blurry. The saddest thing is that no amount of editing can correct this photo. And all because the resolution of the photo on the site is, for example, 900*600 pixels. That is, 1 pixel on the print will have a size of approximately 0.33 millimeters - and it is difficult to count on “ringing” sharpness! And here another image quality parameter appears, with which you can evaluate the quality of the print - DPI

DPI

DPI is an abbreviation for the English phrase Dots per Inch, which is translated into Russian as dots per inch. This value just shows how many image pixels there are per one “linear” inch when printing (an inch is equal to 2.54 cm). There is also a DPC value (dots per centimeter), but it is used less often - whatever one may say, all these printing technologies came to us from where inches, feet, pounds, etc. are used. So, let's return to our example - a picture of 900 * 600 pixels, which we decided to print in a format of 30 * 20 cm. Let's convert centimeters to inches for convenience - we get 11.8 * 8.9". If we divide 900 pixels by 11.8", we get the print resolution 76 DPI. This roughly corresponds to the resolution of the monitor with its “large” pixels, so the picture on the screen looks good. But to get a print of acceptable quality, you need a print resolution of at least 150 DPI, and if you want very good detail, at least 300 DPI. To provide such a resolution when printing 30 * 20 centimeters, the original digital image must have a resolution of 3540 * 2670 pixels - this is about 9 megapixels. So we found the reason why photographs printed “from the Internet” look blurry and cloudy. Now let's return to our question - how to adjust the resolution of the picture so that it is printed at the specified size? As an example, consider preparing photographs for documents.

Creating your own photo for documents - step-by-step instructions

Suppose you need to take several photographs measuring 4*6 cm and place them on a sheet of 20*30 cm. How to do this?

1. Take the original image and open it in Photoshop. Select the menu item "image" - "image size". The following dialog box opens before us:

In the dialog that opens, we see two groups of settings - “dimension” and “print size”. The "dimension" group displays the dimensions of the digital image in pixels. We do not touch these settings! In the “print size” group, set the size we need in centimeters (units of measurement are selected from the drop-down lists). In our case, it is 4*6 cm. We also set the printing resolution to 300 pixels per inch, this will ensure good print quality.

By changing the print size settings, we see that the pixel dimensions also change. That's how it should be! After all this, click OK. The image changes in size. Now we need to copy it - use the key combination:

Ctrl + A (English) - select all
Ctrl + C (English) - copy to clipboard

We will transfer what was copied to the clipboard to a separate canvas, see point 2. 2. Now we need to create a new image that will correspond to a 20*30 cm sheet, which we will go to print in the darkroom. Select the menu "File", "New", a dialog box appears:

We indicate the size of the photo paper on which printing will be done (20 by 30 cm) and set the resolution in pixels per inch to the same as our photo - 300 DPI. Click OK.

3. A blank image with a transparent background appears. Press the key combination Ctrl + V and paste our first image onto a new canvas. It will look something like this:

The image is inserted as a new layer. Move it to the upper left corner, then select the "Layer" menu, "Duplicate Layer".

Another similar picture will appear on the canvas, initially it “lies” on the original layer. We move it and put it next to it. In the same way, we create as many duplicate layers as we need. After this, we flatten the layers (menu "Layer", "Match").

We save the picture in JPEG format, copy it to a flash drive and go to the photo lab. We tell the operator the following - “print this image in 20*30 cm format with a resolution of 300 DPI no scaling"In this case, small pictures will have exactly the size that we indicated for them - in our case, 4 * 6 centimeters. It is advisable to have a ruler with you to check the size of the prints.

Hello! The idea for this post was born a long time ago, but I only got around to it now.

So, imagine a classic situation - a designer asks a client

send a photo for the layout. It would seem, what could be simpler? But it was not there.

The client, without blinking an eye, sends a 500x325 jeep, while knowing

that its layout is A3 size. The designer, of course, is dissatisfied, to put it mildly.
He asks to send a better photo, the client sends a new one 600x425.
The designer is furious.

The client cannot be blamed - he is not obliged to even understand
in fundamentals of computer graphics and printing. But, you must admit,
the world will become much more beautiful if this suddenly happens.

I will try to give the simplest possible algorithm for determining
whether the photo is suitable for printing or not. Go.

The client has a photo in 500x325 resolution and a task
print it on A3 format.

The client has a photo and the task is to print it in A3 size.

Here's a photo:

First, What you need to do is find out her permission.
Photo resolution - number of pixels
horizontally and vertically.

The photo consists of pixels (squares).
If I enlarge it we can see them.

Our task is to find out how many pixels fit in a photo
horizontally and vertically.

The simplest and affordable way which I know -
This is Google images.

So:
1) Go to google.com and click “Pictures” in the upper right corner:
2) Take our photo and drag the cat to the search bar with the mouse

3) We get the result

The resolution of our photo is 500X325 pixels:

Next step.
Now there will be a little theory. Very little.

Many of you have probably heard about this magical combination.
like “300 dpi” - it’s usuallythey say when talking about quality printing.
Let's figure out what it is and why we need it.300 dpi —
or 300 dots per inch or 300 dpi, or print resolution.

will fit 300 pixels of the image. DPI - digital image parameter,
which you don’t need to worry about at all - the designer will exhibit it.

By the way, when they say dpi, they mean ppi - pixels per inch or pixels per inch,
which is a more correct term, because dpi is a parameter that describes
printer resolution, i.e. how many dots per inch it can print.
Typically, dpi requirements are much higher in the numerical dimension and 300 dpi is
This is a very low printer resolution.

But! I suggest you don’t worry and say dpi, because... you don't care
will understand correctly.There is no point in fighting this - everyone is used to saying dpi

(like diapers instead of nappies).300 dpi is such a generally accepted
quality standard for printing.The lower it is, the less clear
there will be picture details.It is believed that if every
300 pixels of the image will fallfor every inch of you
printed image -it will look high quality and sharp.
This is where we got toto the second misconception.
The thing is, no one will ever tell youwhat is quality
image. No one will ever ask you the criteria for sharpness.
At a minimum, quality (which does not exist) is task-based.

For example, if we print a billboard with a resolution of 50dpi,
then upon closer inspection it will look soapy,
details will be fuzzy and... uh... your favorite quality will be low.
But the trick is that they look at the billboard from a sufficient distance,
so that low image quality spoils the picture.
From afar, you will see everything clearly. It turns out 50dpi is not equal
poor quality image.

The same can be said about printing. The leaflet in your hands will allow
you need to look more closely at the details of the image, which means the resolution
To print a leaflet, it must be 300 dpi!But in reality not always.
It can be, for example, 225dpi and the quality will suit everyone, because

that the image, for example, will not contain small and important details,
and the degree of vagueness will be quite acceptable.

I suggest discarding such things as billboards and banners,
and consider exclusively printing for convenience
and take into account that the output we should have is
uh.. maximum sharpness and... uh.. image quality.

So our choice is 300dpi (actually ppi, but for nerds like me)

Let's return to our cat.
Let me remind you that we need to print it on A3 format, the photo resolution is

500x325 pixels. To make the cat sharp, every inch
our A3 image should be 300 pixels.

Let's now take a calculator and calculate what
size at this resolution we can print a cat,
so that it wouldn't hurt to look into his eyes.

To calculate the horizontal size:

500px / 300 (pixels in each inch) is approximately equal to 1.6 inches or 4 cm.

We conclude - printed image required quality will
be only 4 cm in length with a horizontal resolution of 500px,
those. You cannot send it to the designer, because... we need to print as much as 42 cm!

To find out the resolution of the image we need, we only need
how many inches will our image be: 42/2.54= 16.5
Then multiply this amount by the 300dpi printing standard: 16.5x300 =
4800px horizontally.

If you found a photo on the Internet, then there is a chance that everything will be there
lie the same, but largerpermissions. We open our window again,
in which we recognized the resolutionfirst photo and click on the link
"All sizes"

Looking at the search results

Maximum photo resolution we can download
this is 2640X1650 pixels, which is also not enough for printing
on A3 format, following our rule.But it is not all that bad.
Let's remember that quality is a conceptrelative
and, in fact, non-existentand you always need to start from the task.
Do you need an A3? Ok, but for what?It's uncomfortable to hold in your hands,
Most likely hang it on the wall.And if so, then look
they will be at him at a distance,those. slightly soapy parts
will not spoil the whole picture.

Let's do an experiment. We'll send both photos to the designer.
The designer, having received our photos, created an A3 size document,
with a resolution of 300dpi and inserted both of our photos.

Here is the size ratio of what you should get
and actual photo sizes.

This photo is 500x325

This one is 2640X1650

As we see, in both cases the resolution is not enough, and in order
fill the entire document space, designer
You'll have to stretch both photos.Let's see what he has
it turned out after increasing:

The photo on the right, despite the fact that it was not up to 300dpi in resolution,
looks quite good, which cannot be said about the left photo

But in any case, you can say with a clear conscience that you did everything
to save the designer’s time and nerves.

But that is not all. From all that has been said above, we can conclude that
that the higher the resolution, the best quality we will receive a print.
This is not entirely true. Look here, I found a photo of the cat in the required resolution
(4800x3120) for printing on A3

The naked eye can see that the picture is far from sharp, despite its 4800x3120

Why? It’s simple - it’s either a photo marriage (the focus was not adjusted when shooting),
or someone took this low-resolution photo and stretched it to a larger one.
Of course, this did not add sharpness to the image. And the designer can’t help here.
So before you rejoice high resolution photos,
make sure that on the screen
she looks decent.

Oof! Let's summarize.

Before sending a photo to the designer, you need to follow these steps:
1. Know what size you need the output layout.
2. Find out the resolution of your photo.
3. Calculate the capabilities of this resolution on a calculator,
those. What is the maximum size it can be printed?
at a print resolution of 300dpi.
For this:
1) divide the number of horizontal pixels by 300 - we get the number of inches,
2) Multiply this number by 2.54 and get the number of centimeters

4. If the resulting size is equal to or larger than the required dimensions,
we can safely send it to the designer, but after making sure
that the photo itself is sharp and there is no noise, artifacts and other nasty things on it.
5. If the resulting size is smaller than required, go to Google
(we take a camera, rummage around on our computer) and look for a photo of the maximum size.
6. Having found it, we perform the calculations again.
7. If the new permit is again not enough, we send
This is a photo to the designer with the words “This is the biggest we could find.”
8. We wait for an answer and act according to the situation.

Do you feel like the world is becoming a little more beautiful?