How to Check Image Size & Resolution


In this video, I’ll show you how to check the size and resolution of your images using Adobe Photoshop. There are many different programs you can use to view your images, and most of them will allow you to access the image’s properties or attributes from the ‘Menu’ bar. If you can't find the size and resolution in one program, try another. If all else fails, you can always send the image to us and we can check it for you.

First, let’s briefly review the requirements and then we’ll go into Photoshop to check for them.

Image Size & Resolution Requirements

If you are submitting images for your book’s cover or interior, they need to have a resolution of no less than 300 PPI, Pixels Per Inch. In addition, images should be submitted at the size you want them to be printed.

For interior images, we recommend at least 6 inches tall for portrait-oriented images or 6 inches wide for landscape-oriented images. If you are publishing a color book and would like your interior images to be Full Bleed, or extend to the edges of the page, add ¼ inch of Bleed Space to the top, bottom, and outside edge of the page to get your final minimum image size. Keep in mind that this outside ¼ inch of your image will be cropped off at the printer. Unfortunately, we cannot do Full Bleed images in our black and white books.

For cover images, we recommend they be slightly bigger than the cover itself, adding a 1/8 inch of Bleed Space to the top, bottom, and right-hand side of the cover. Again, keep in mind this 1/8 inch of Bleed Space will be cropped off at the printer, but it is necessary in order to accommodate a Full Bleed image.

Now, in order to demonstrate how size and resolution work together, I have a few examples I’d like to show you. First, let’s look at this photo. Let’s say we’re interested in placing this image on a page inside a 6 x 9 book. Since the image is landscape-oriented, we suggest that it be roughly 6 inches wide. In Adobe Photoshop, you can check the size and resolution by going to ‘Image’ and ‘Image Size’. In the window that pops up, you see that the image is 6 ½ inches wide, which is a good size. Unfortunately, the resolution of the image is only 150 Pixels Per Inch, only half the resolution of what is required for publication.

However, in Adobe Photoshop and some other programs, you are able to change the size or resolution of an image. But when doing this, you need to be very careful that changing one aspect of the image doesn’t negatively affect another aspect. For example, if we change the resolution of this image to the required 300 PPI, you’ll see that the image gets smaller. It is now only 3 ¼ inches wide, no longer big enough to fit the width of the text margins. But there is one other solution when using Photoshop or other image manipulation software. Before changing the resolution, make sure ‘Resample Image’ is selected. And if you have the option, choose a bi-cubic setting to help smooth out image enlargement. Now, when we change the resolution to 300 PPI, the width and height remain the same. This process is called ‘resampling’. And while it might get your image to reach the technical requirements of our printer, it is not always a perfect solution.

When you resample an image this way, it might look blurry or pixilated. Sometimes, like in this example, the trade-off is acceptable. But other times, you will notice the quality of your image degrade so badly that the only remaining option will be to rescan the original photograph or artwork if you have it. If you have the original hardcopy image but are not able to rescan it yourself, you might be able to find scanning services at your local office supply store. We also offer our own scanning services. If sending an image for scanning, we recommend making a high-quality photocopy for submission so that you don't take the chance of losing your original image in the mail. See our Fee Schedule or contact a representative to learn more about our scanning services.

Let’s look at another photo. Let’s say we want this image to be as big as possible in a 5 x 8 sized book. By going to ‘Image’ and ‘Image Size’, we can see that this photo is only 2 inches wide and just over 3 inches tall, not nearly big enough to fill the text margins of a 5 x 8 size page. It’s resolution is also very low, only 72 PPI.

Incidentally, 72 PPI is the standard resolution for images on the internet. Their low resolution makes them faster to download when you’re surfing the net, but it makes them bad candidates for publication. So if you’re pulling images off the web, you’ll want to make sure to check their resolutions and that you have legal permission to reproduce them.

Let’s see if we can change this image’s properties to meet printer requirements. If we select the ‘resampling’ button and change the resolution to 300 PPI, we could use this image, but it would only be 2 inches tall. If we tried making it any bigger, it would lose resolution and become blurry or pixilated. If you zoom in on the image, you can see what this looks like. This is what would happen if we tried to make the image fill the margins in a 5 x 8 book. It just isn’t possible. The only solution would be to rescan the original photograph at a higher resolution.

Now, let’s look at a couple of images we might want to use on the cover of a book. Let’s say we want this photo to fit width-wise across the middle of the front cover and our book size is 6 x 9 inches. The image is 6 inches wide, almost big enough to fit the width of the cover. Remember that when trying to fill a cover, you have to add a 1/8 inch of Bleed Space to the top, bottom, or outside edge. In this example, the image wasn’t going to touch the top or the bottom of the cover but it was going to touch up against the outside edge. In that case, the image would need to be at least 6 1/8 of an inch wide. We also notice that the resolution of the image is only 250 PPI, slightly less than the required 300. It would be best to rescan this image if possible. But, if you do not have the original hardcopy image, you might be able to resample the image to meet printer requirements.

First, select the ‘Resample Image’ button. Then, change the resolution to the required 300 PPI and change the width to 6 1/8 or 6.125. Click ‘Okay’. Next, it is a good idea to go to ‘View’ and ‘Actual Pixels’. If you think the image still looks pretty crisp and clear, it is probably safe to use on your cover. But, if you notice any loss of quality, it is better to try rescanning the original hardcopy image or find another image to use.

Let’s look at one more image. Let’s say this image is an original painting you made to fill your 6 x 9 cover. Remember that in order to fill a cover, you have to add 1/8 inch of Bleed Space at the top, bottom, and outside edge of the cover.

When we look at its properties, we see that it is 300 PPI. The width of the image is 6 ½ inches, a little more than the minimum of 6 1/8 for this example. The height of the image is a little more than 7 ¾. If we wanted the image to fill the 6 x 9 cover, the height would need to be 9 ¼ inches, including 1/8 inch at the top and 1/8 inch at the bottom for Bleed Space. This image could fit the width of your cover but it could not fit the height. It just doesn’t have the right dimensions.

If you could rescan this image so that the height were 9 ¼ inches, you could then crop the sides of the image until it fit the width of the 6 x 9 book cover. When creating original artwork for your cover, it is a good idea to know the dimensions of your book’s final cover before beginning and to keep in mind that the outer 1/8 inch at the top, bottom, and outside edge will be cropped off at the printer.

If you have any questions about images, please contact a representative at 1-888-728-8467 and we’ll be happy to assist you.