Why yes we did. Take a look once again at the Document Size section:. Look what values it's giving us for the width and height of our image - 48 inches for the width, and 32 inches for the height. Exactly what we came up with ourselves when we divided the number of pixels wide and the number of pixels high by 72 pixels per inch the resolution.
And that's really all that image resolution is. It's how many if your image's pixels will print inside every inch of paper, which then tells us how large the image will be when it's printed. Keep in mind as we're going along that I keep saying "printed". I can't stress enough, and this is the number one reason why so many people have a difficult time grasping the concept of image resolution, that resolution means absolutely nothing until you go to print the image.
It has absolutely nothing to do with how your image appears on your screen. Just to prove there's nothing up my sleeve, let's change the resolution value of the photo from 72 to, oh, let's make it , which will mean that for every inch of paper when we go to print our image, of our image's pixels will be printed from left to right and again from top to bottom.
You can see the change in the screenshot below:. Now, since of our image's pixels from left to right are going to be fitting inside every inch of paper as opposed to only 72 pixels, it stands to reason that it's not going to take 48 inches of paper to fit the entire width of our photo into.
Likewise, since of our pixels from top to bottom are going to be fitting inside every inch of paper as opposed to only 72 pixels, it shouldn't still take 32 inches of paper to fit the entire height into. Just for fun, let's do the simple math ourselves. Once again, all we need to do is divide the width in pixels and the height in pixels by the resolution in pixels. According to my math, when I take pixels wide and divide them by pixels per inch, that gives me Likewise, pixels high divided by pixels per inch gives me 7.
In other words, when I take my photo that's pixels wide by pixels high and print it at a resolution of pixels per inch, my photo will be Let's take a look at what the Document Size section is telling us. Am I right? Looks like my math skills are stronger than ever okay, so I used a calculator. Photoshop is showing us exactly what we expected, that at a resolution of pixels per inch, it will take To summarize then, all "image resolution" means is how many of your image's pixels will print inside every inch of paper.
Again, it has no effect at all on how your image appears on your screen, since your monitor has nothing to do with your printer. There's one other aspect that image resolution has to do with, and that's the size of the pixels when you go to print the image. It makes sense, really. These two acronyms are often used interchangeably although they do have different meanings.
The physical size of an image refers to the dimensions in which it would print ex: 8. The memory size is how much memory an image file takes up on a hard drive. For example, a JPG image saved on a computer may be 2 MB megabytes , meaning that it will require 2MB of space on a drive to store that image.
Image resolution is typically described in PPI, which refers to how many pixels are displayed per inch of an image. Higher resolutions mean that there more pixels per inch PPI , resulting in more pixel information and creating a high-quality, crisp image. Images with lower resolutions have fewer pixels, and if those few pixels are too large usually when an image is stretched , they can become visible like the image below.
When you change the resolution of an image, you are saying how many pixels you want to live in each inch of the image. For example, an image that has a resolution of ppi will contain pixels within each in of the image. Now, compare that to an image with 72ppi, which has a lot fewer pixels per inch.
As you've probably guessed, it won't look nearly as sharp as the ppi image. It's better to have more information than not enough! It's much easier for image editing applications, like Photoshop, to discard any unwanted image information reducing the size of an image than it is to create new pixel information enlarge an image.
The final size of your image depends on the resolution that you choose. If an image is x pixels it means that it will print at 15 x 10 inches if you set the resolution to dpi, but it will be While the size of your print does change, you are not resizing your photo image file , you are just reorganizing the existing pixels.
Because of the aforementioned correlation between size and resolution, a lot of people think that megapixels equal quality. And in a sense it does because the more pixels you have to spread out, the higher the pixel density will be. However, on top of the quantity you should also consider the depth of the pixels, this is what determines the amount of tonal values that your image will have.
In other words it is the number of colors per pixel. For example, a 2-bit depth can store only black, white and two shades of grey, but the more common value is 8-bit. This is already more that the eye can distinguish which means that bit or bit will look relatively similar to us.
Of course, this means that your image will be heavier even of the size is the same, because there is more information contained in each pixel. This is also why quality and quantity are not necessarily the same.
Therefore quantity helps, but also the size and depth of each pixel determine the quality. Click here for more details on this and other titles in the Pocket Guide series.
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Image Size and Resolution Requirements. Image Sharing, Display and Preservation.
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