Camera resolution and photo size. Resolution (computer graphics)

The calculators in this article focus on the topic of digital photo printing.

The first calculator helps you choose the photo format for printing images of known sizes. Let's formulate the problem.

Given: We have a digital image of known sizes, for example, 3264 by 2448 pixels, and a set of standard formats offered by photo printing services. The format determines the linear dimensions of the photograph, for example, a 10x15 photograph has dimensions of 102 by 152 millimeters.

Required: Choose from a set of formats as large as possible, on which you can still print an image without loss of quality.

To set the photo formats, I have created a separate reference book Photo Formats, which can be expanded if necessary.

The only special knowledge that you need to have to find the answer is the knowledge that high-quality printing of a digital image requires a resolution of at least 300 dots (pixels) per inch (300 dpi), and more or less acceptable printing is possible at a resolution of at least 150 dots per inch (150 dpi). Everything else is simple math.

The task is graphically shown in the figure below.

The search logic for the answer is simple - the linear dimensions of each format are converted into inches, and then into pixels, based on the fact that there are 300 (150) pixels in one inch. Next, the resulting number is compared with the size of the image (there are certain nuances associated with the ratio of height and width, but more on that in the second part). If the size of the format in pixels is larger than the size of our image (in the figure - the format is to the right of the photo), then it will no longer fit, because the photo will have to be stretched, and we will get a resolution worse than 300 (150) dpi. If the format size is smaller than the size of our image (in the figure - the format to the right of the photo), then it will do - the photo will have to be compressed, and we will get a resolution better than 300 (150) dpi.

Of all the suitable formats, the calculator selects the format of the maximum size (there are no problems with printing images of a smaller size - as far as I understand, you can print at 1200 dpi).

Format size in pixels for 300 dpi

Format size in pixels for a resolution of 150 dpi

The second calculator by the size of the already printed image and the size of the original image helps to determine the resulting image resolution and the part cropped when scaling. Let's formulate the problem.

Given: An image of known dimensions is printed on a photograph of known dimensions. Since the value of the ratio of the height and width of the image and the value of the ratio of the height and width of the digital image, as a rule, do not coincide, then when printing, the image is scaled, obviously, while maintaining the proportions. This is shown graphically in the figure below.

When scaling, as you can see, two options are possible:
the first is scaling with loss of part of the image,
the second is scaling with the preservation of the entire image, but with the appearance empty space in the picture.
As an esthete, I chose the first option for calculations.

Thus, the first thing you need to do is find the resulting image resolution and the part of the image that was not included in the image. Second, accordingly, it will be the difference between the used width (height) and the original width (height) of the image.

Width of the printed image, cm

Height of the printed image, cm

Image width in pixels

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, preparing it for printing is sometimes difficult to deal with 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 photo for documents. You can go in two ways - go to a photo studio and take a picture there, paying 150 rubles for 4 small photographs printed on a sheet of 10 * 15 cm. The second option is to take a picture at home, prepare an A4 sheet for printing, on which you can squeeze so many of your photos of different sizes that enough for several years to come. Then you go to a photo studio and print your creation on A4 sheet of rubles for 30 rubles. It seems that there is a ridiculous benefit from one order, 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 substantial amount. And this is just one example. Another question is how to keep the size of the photos so that they are exactly 4 * 5 cm on the print (or some other size). In order to adjust the size of the print to the required one, you need to understand the connection centimeters, pixels and dpi.

Pixels

A pixel is one point that makes up an image. Also called a pixel is a cell of an image on a monitor or LCD TV. Take a close look at the monitor and you will see a barely noticeable mesh, one cell of this mesh 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 is 6.000 * 4.000 = 24.000.000 pixels or 24 megapixels. When viewed on a monitor, the picture 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 real resolution of the photo is less than what we want to see - the pixel size in the photo has become larger than the pixel size on the monitor.

Centimeters

I think there is no need to explain what a "centimeter" is. In our case, the size of the photo prints is measured in centimeters. Usually photographs are printed with a size of 10 * 15 cm, but sometimes larger formats are used - 20 * 30 cm (approximately corresponds to A4 size), 30 * 45 cm (A3) and more. You probably faced a problem - you found on some website beautiful photo and decided to print it large format(for example, 20 * 30 cm), but after printing, we noticed that the quality of the print is not very good - the contrasts of objects turned out to be a little blurry. What is the saddest thing is that no processing of this photo can be corrected. 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 about 0.33 millimeters - while it is difficult to count on "ringing" sharpness! And here another parameter of image quality appears, with which you can evaluate the quality of the print - DPI.

DPI

DPI reduction English phrase Dots per Inch, which translates into Russian as dots per inch. This value just shows how many image pixels are per one "linear" inch when printing (an inch is 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 900 * 600 pixel picture, which we decided to print in 30 * 20 cm format. We translate centimeters into inches for convenience - we get 11.8 * 8.9 ". If we divide 900 pixels by 11.8", then we get the print resolution 76 DPI... This roughly corresponds to the resolution of the monitor with its "large" pixels, so the picture looks good on the screen. 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, which is about 9 megapixels. So we found a reason why photos printed "from the Internet" look blurry and blurry. Now back to our question - how to adjust the image resolution so that it is printed at a given 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 4 * 6 cm photos and place them on a 20 * 30 cm sheet. 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. Do not touch these settings! In the "print size" group, set the desired size in centimeters (units of measurement are selected from the drop-down lists). In our case, it is 4 * 6 cm. We also set the print resolution - 300 pixels per inch, this will ensure good print quality.

By changing the settings for the print size, we can see that the dimensions in pixels also change. It should be so! After all this, press the OK button. The image is resized. Now we need to copy it - use the keyboard shortcut:

1. Ctrl + A (eng) - select all
2. Ctrl + C (eng) - copy to clipboard

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

We indicate the size of the photo paper on which the printing will be performed (20 by 30 cm) and set the resolution in pixels per inch to the same as our photo has - 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 choose the menu "Layer", "Duplicate layer".

Another similar picture will appear on the canvas, initially it "lies" on the original layer. Move it and place it next to it. In the same way, create as many duplicate layers as we need. After that, flatten the layers (menu "Layer", "Flatten").

Save the picture in JPEG format, copy it to a USB flash drive and go to the darkroom. 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 same size as we indicated for them - in our case 4 * 6 centimeters. It is advisable to have a ruler with you to check the dimensions of the prints.

Updated: 07 June 2018 07 June 2018

I propose to consider what kind of animals they are - JPG and RAW photo formats, what they affect and when you should pay attention to them. What is the photo size and file weight, how they are measured and what they depend on.

Almost all photo cameras can save photos in JPG format (even cameras of phones and tablets). In all mirrors and without SLR cameras, as well as in advanced compacts, in addition to JPG, there is at least RAW and RAW +, and sometimes TIFF.

To understand the formats, first you need to agree on what is meant by the "size" of the photo and the "weight" of the file (photo). I propose to consider these concepts on more tangible objects ... for example, on goodies.

1 | What is a pixel:

The size of objects is measured in meters, the size of a photo is in pixels (px).

If you measure the size of this vase with berries, then it will be somewhere 10 centimeters in height and that way 13 centimeters in width ... approximately. That is, we are used to measuring objects in centimeters (meters, kilometers, and so on). If we talk about the photo of the same vase, then the original size of the photo is 7360 pixels (px) wide by 4912 pixels (px) high. This is the maximum photo size my Nikon camera... To post this photo on the site, the photo size has been reduced to 1200px by 798px (why, I'll tell you a little later).

What is a Pixel? Photos taken by digital cameras or digitized on a scanner are a combination of tiny colored squares - pixels... If you zoomed in any photo, you will see these pixels. The more such pixels in the photo, the more detailed the picture.

A fragment of a photo enlarged a thousand times - squares of pixels are visible.

2 | Can pixels be converted to centimeters:

This is exactly what happens when you need to print photos on paper. Here you need one more indicator - the pixel density (resolution), which the printer (or other machine for printing photos) can print. The printing standard for photographs is 300 dpi (dpi is the number of dots per inch). For example, photos with a resolution of 300 dpi are used for printing in beautiful glossy magazines.

So that you don't rack your brains over dividing the photo size by resolution and convert inches to centimeters, in any program for viewing and editing photos (for example, in Photoshop) there is a function for viewing the photo image size in centimeters. You will need it to understand what is the maximum size of a photo in good quality(with a resolution of 300 dpi), you can print on paper or other material media.

For example, this photo with tropical Frangispani flowers can be printed in 61 cm by 32 cm.

Photo size in pixels and centimeters in Photoshop

To find out the size of the photo in pixels and centimeters in Photoshop, you need to press the Alt + Ctrl + I key combination or go to the Image menu (Image) Image size (Image size).

Let's go back to the reality of digital photos - to pixels and photo sizes in pixels. What happens if you decrease the number of pixels in a photo? The answer is that the quality of the photo will deteriorate. For example, I took a photo of the same vase with berries that at the beginning of the article and reduced the size of the photo to 150 pixels wide. With this reduction, the program destroys some of the pixels. The photo has become miniature:

Now let's try to "stretch" the photo to the full page:

The stretched picture looks cloudy and indistinct

As you can see, the detail is not the same, since some of the pixels (and with them the details) are missing.

Of course, if you use this thumbnail as a small icon or a small image in a Power Point presentation, it will look quite normal, but for printing in a magazine on half a page, it is clearly not suitable.

3 | What size of the photo (how many pixels) is optimal:

If you plan to print a photo someday, then save photos in the highest possible resolution, which only your camera will allow (carefully read the instructions for your camera to properly adjust the photo size).

In some cases, you need to reduce the size of your photos. As I wrote above, for the site I reduce the photo size to 1200 pixels on the long side. If you upload a photo in full size, the pages of the site will take a very long time to load, and many visitors may not like this (not to mention the search engines Google and Yandex).

The size of photos is measured in pixels (px). The number of pixels determines the size of the photo on the screens of monitors, and what size you can print the photo.

4 | File size or "photo weight":

Now let's deal with the "photo weight". It just so happened historically that there is a lot of confusion on this issue and the file size is often referred to as "photo weight", which is more convenient than correct. File sizes are measured in megabytes (MB) or kilobytes (KB). And here it is worth remembering that, unlike kilograms, where 1 kg = 1000gr, 1 megabyte = 1024 kilobytes.

How it looks in practice: let's imagine a situation that your camera has a memory card with 64GB (gigabytes) written on it. If you look at how many bytes there are (select "properties" on the computer with the right mouse button), it turns out that there are 63567953920 bytes on this memory card and this is equal to 59.2 GB. How large the files your camera creates depends on how many photos will fit on this memory card. For example, I have 830 files with photos in RAW format (read about formats below).

What determines the file size:

• First, the size of the photo (what is measured by pixels): the file with the first photo of berries (photo size 7360x4912 px) is 5.2 MB, and it, reduced to 150 px, will "weigh" 75.7 KB (in 69 times less).
• Secondly, from the format (JPG, TIFF, RAW), which is described below.
• Thirdly, the file size (or "photo weight") depends on the amount of details: the more there are, the "heavier" the photo (which is most relevant for the JPG format).

More details - more weight

For example, here in this photo with monkeys from Sri Lanka there are many small clear (in the language of photographers, "sharp") details and the file size with this photo is 19.7MB, which is significantly larger than berries in a vase on a white background (5.2MB).

If you ask what size photo can I print from a photo that weighs 2MB. Nobody can answer you until they know the number of pixels. And it is better, of course, to look at the photo as well, since some craftsmen like to get a photo from the depths of the Internet, increase the number of pixels programmatically, and then want to print it on the cover of a magazine. It turns out as in the example above with a stretched photograph of a vase with a width of 150 px.

File size (often referred to as "photo weight") is measured in megabytes (MB) or kilobytes (KB) and depends on the format, pixel size, and detail of the photo.

5 | Photo formats:

And, finally, we come to the issue of image formats and the type of file compression, which also affects the size of the file with the photo.

Almost all photo cameras can save photos to JPG format(even cameras on phones and tablets). It is the most common image format and is "understood" by all computers and image viewers. In JPG format photos can be uploaded to social network, upload to blog, add to Word files, Power Point and so on. JPG can be processed in Photoshop, Lightroom and other image editing programs.

From my practice: if I want to take a photo for a social network and quickly upload it, then I either take a photo on my phone or put the jpg file format in my camera.

One thing to remember about the jpg format is that it is a compressed format and has compression ratios. The higher the compression ratio, the smaller the file size due to the reduction in detail and quality of the photo. Therefore, multiple editing and re-saving (re-compression) of the same photos in jpg format is not recommended.

When saving a file in jpg format, the compression level is selected (example from Photoshop).

In all DSLRs and without DSLRs, as well as in advanced compacts, in addition to JPG, there is at least RAW, and often also TIFF.

A bit of theory:

• Tiff(English Tagged Image File Format) is a storage format for raster graphic images (including photos). TIFF has become a popular format for storing deep color images. It is used in printing, widely supported by graphics applications.
• RAW(English raw - raw, unprocessed) - format digital photography containing the raw data obtained from the image sensor (the thing that replaced the film in digital cameras).

Personally, I never take pictures in TIFF format. I can't even think of why I need this, if there is RAW. I can use uncompressed TIFF to save photos that I still plan to finalize in Photoshop.

6 | Advantages and Disadvantages of RAW Format:

I almost always have a RAW format in my camera, since I'm going to process (edit) a photo in Lightroom or Photoshop. RAW has a number of significant disadvantages:

• There is no way to view files without conversion. That is, to view photos in RAW format, you need a special program that supports this image format.
• Larger file size than JPEG (from my camera

Many of us love to photograph. Diversity and availability digital cameras make photography a popular pleasure to capture the vivid, colorful moments of our lives. Wherein high quality of the received photos, does not guarantee the same quality when printed digital images on standard roll photo paper. In this material I will tell you what are the sizes of photos for printing, I will give tables of available formats, and I will also give a number of examples that make it possible to clearly understand the features of different sizes of photos.

Understanding the size of photos for printing

To understand what are the sizes of photos for printing and what are their specifics, we need, first of all, to understand basic concepts required to understand the digital printing process.

Linear photo size- dimensions of the photograph in millimeters (width-height).

Photo parameters in pixels- the dimensions of your photo, expressed in the number of pixels (width-height).

Pixel- the smallest element of the image, usually a rectangular or circular point, and of a certain color. An image consists of hundreds or thousands of such pixels, which are counted both horizontally (width) and vertically (height). For example, an image size of 1181x1772 (usually corresponding to the standard 10x15 photo size) is 1181 pixels wide and 1772 pixels high.

Moreover, the more such dots-pixels in your image, the usually better it is, with better detail and rendering of objects.

Aspect ratio- the aspect ratio of the photo (for example, 1: 1, 2: 3, 3: 4, and so on). The parameter shows how much one side is shorter or longer than the other.

Bitmap (raster)- an image consisting of such pixels.

DPI- (abbreviation for "dots per inch" - dots per inch) - a parameter used to characterize the resolution of printing photos, that is, the number of dots per inch (inch is 2.54 cm). The basic printing standard is 150 dpi, the optimal one is 300 dpi. Accordingly, the higher the DPI, the higher the print quality of the existing digital photo.

Photo standard (format) Is a stereotyped aspect ratio of a photograph, which is important to adhere to in order to obtain the final image on paper.

Why it's important to consider standard photo sizes

In the vast majority of cases, your digital photographs will be printed on photo paper that has standard sizes. If the proportions of digital photographs and the selected sizes of photographic paper do not match, the photographs may come out stretched, not clear, lose the quality of the image, and have other undesirable consequences for you.

Therefore, it is important to measure the standard print sizes of your photographs against the pixel sizes of your digital photos in order to select the optimal print format.

Popular photo sizes for printing with a table of formats

The generally accepted photo standard is 10 by 15 cm. In this case, the size of a commensurate digital photo is usually slightly larger (for example, 10.2 by 15.2 cm), and the size in pixels of this photo will be 1205 by 1795 pixels.

Other formats are shown in the table below:

If you plan to work with large-format printing, then it has fairly broad requirements for a digital image:

If you know the dpi parameter and the number of pixels of your photo, then using the formula below, you can calculate the required dimensions of the sides of your photo:

In this formula:

x is the required size of one side of the photo in centimeters;
r is the resolution of the side of the photo in pixels;
d - 2.54 cm (standard inch size);
dpi - usually 300 (less often - 150).
For example, let's say the width of the image is 1772 pixels and dpi = 300.
Then 1772 * 2.54 / 300 = 15.00 cm in print width.

Popular photo formats

In addition to the classic 10 by 15 (A6 format) I have already mentioned, there are other popular photo sizes for printing. Among them, I would highlight the following:

Conclusion

This article has given the standard photo sizes for printing, popular photo formats, as well as a convenient formula for calculating the optimal sizes of the sides of a photo. I recommend sticking to the formats I listed, this guarantees the quality of the printed photos, and therefore the visual pleasure of viewing them.

We present to your attention our selection of the most big photos in the world. You will need FlashPlayer to view them. You can download it separately or use the Google Chrome browser.

Photo-panorama of the Moon - 681 Gpc.

The absolute champion in composite photo size is NASA. In 2014, the agency published a 681 gigapixel panorama of the moon. On June 18, 2009, NASA launched the Lunar Reconnaissance Orbiter (LRO) to map the lunar surface and collect measurements of potential future landing sites, as well as for scientific purposes.

You can see the panorama on the website.

Photo panorama of Mont Blanc - 365 GPK.

At the end of 2014, an international team of professional photographers led by Filippo Blenini made a circular panorama of the mountain range between France and Italy - Mont Blanc, the second highest mountain in Europe after Elbrus.

It consists of 70 thousand photographs! Photos taken Canon camera EOS 70D with Canon EF 400mm f / 2.8 II IS telephoto lens and Canon Extender 2X III. The creators of the giant panorama claim that if printed on paper, it will be the size of a football field. This is the largest gigapixel photograph taken on earth to date.

You can view the panorama on the project website.

Photo panorama of London - 320 GPK.

The panorama was compiled from 48,640 individual images taken with four Canon 7D cameras and posted online in February 2013. Preparation for the experiment took several months, and filming took place over four days. Pictures taken by British Telecom from the top of the BT Tower, located in central London on the north bank of the Thames. Photographed by 360cities.net experts Jeffrey Martin, Holger Schulze and Tom Mills.

You can see the panorama on the website.

Photo panorama of Rio de Janeiro - 152.4 GPK.

The panorama was taken on July 20, 2010 and consists of 12,238 photographs. It took the author almost three months to upload the final image to gigapan.org!

You can see the panorama on the website.

Photo panorama Tokyo - 150Gpk.Fo

Panorama by Jeffrey Martin, founder of 360cities.net. The panorama was created from 10 thousand different images taken from the observation deck of the Tokyo Tower TV tower. When creating it, the photographer used Canon EOS 7D DSLR and Clauss Rodeon robotic car. It took two days to get 10 thousand frames, and three months to bring them into one panorama.

You can see the panorama on the website.

Photo panorama of the Arki National Park - 77.9 GPK.

The panorama was made by Alfred Zhao. "Arches" is a national park located in the USA, Utah. There are more than two thousand arches formed by nature from sandstone. It took 10 days of processing to create the panorama, 6 TB of free hard disk space and two days of uploading the final image to the site. The photo was taken in September 2010.

You can see the panorama on the website.

Photo panorama of Budapest - 70 GPK.

In 2010, a team of enthusiasts sponsored by Epson, Microsoft and Sony created the largest 360-degree panoramic photography in the world to date. The project was named “70 Billion Pixels of Budapest”. The 70-gigapixel photo was taken for four days from the city's 100-year-old observation tower. The panorama was more than 590 thousand pixels wide and 121 thousand pixels high, and total pictures - about 20 thousand. Unfortunately, the link to it does not work right now.

Photo panorama on Mount Corcovado - 67 GPK.

This photo was taken on Mount Corcovado in Rio de Janeiro, Brazil, where the statue of Christ the Redeemer is located. The photo panorama was taken in July 2010 and was created from 6223 frames.

You can see the panorama on the website.

Photo panorama of Vienna - 50 GPK.

The gigapixel photo panorama of the Austrian capital Vienna was created in the summer of 2010. It took 3,600 shots to make it, but the result was worth it.

You can see the panorama on the website.

Photo panorama of Marburg - 47 GPK.

Marburg is a university town with a population of about 78 thousand. The panorama took 5,000 shots, which were taken with a Nikon D300 camera with a Sigma 50-500 mm lens from a 36-meter tower. Each of the photographs has a size of 12.3 Mpc. It took the author 3 hours 27 minutes to shoot, and the total amount of information he received took up 53.8 GB on the hard disk.

You can see the panorama on the website.

Milky Way - 46 Gpc.

For five years, a team of astronomers from the Ruhr University used an observatory in the Chilean Atacama Desert to track our galaxy and create a giant 46 billion-pixel photograph of the Milky Way that weighs 194 GB.

You can see the panorama on the website.

Photo panorama of Dubai - 44.8 GPK.

Panorama by Gerald Donovan. Dubai is the largest city in the United Arab Emirates. To create a panorama was used Canon camera 7D with 100-400 mm lens. The author worked for over three hours in 37-degree heat and took 4250 photographs.

You can see the panorama on the website.

Photo panorama of the backyard - 43.9 Gpc.

4048 photos for the panorama were taken on August 22, 2010 in the village of Round Lake in Illinois, USA. The author, Alfred Zhao, used a Canon 7D camera with a 400 mm lens. It took two hours to shoot, but about a week to process the photos.

You can see the panorama on the website.

Photo panorama of Paris - 26 GPK.

Panorama by Martin Loyer. At the end of 2009, an interactive website www.paris-26-gigapixels.com appeared on the Internet, which has a huge gigapixel photo panorama of Paris with a very clear resolution, consisting of 2346 photographs, which will allow you to immerse yourself in the image of this city and see its sights without leaving the house.