ppi resolution – pixels to inches
What does resolution mean? How about ppi resolution?
About ppi resolution, and pixels to inches. What does resolution mean anyway? Let’s look at resolution for high-quality book printing. We pride ourselves on our knowledge of fine, high-quality book printing. This also includes an understanding of resolution. We are going to look at resolution, pixels to inches, and how it may be useful online.
What is the meaning of resolution?
We ask for images that are 300 ppi resolution, AND at the size they will be when printed in the book.
In electronic imaging, it is how we measure quality in accurate image reproduction, by measuring the number of dots per inch. Dots … we used this word because before electronic imaging we used the number of dots per inch. Now you have the answer to “What does resolution mean?” But, there is more to understanding pixels to inches.
How about ppi resolution?
Previously, we used the term dpi, or dots per inch. Now it is correct to say ppi, or pixels per inch. If asked what does resolution mean, you have an answer. Now you know the difference between ppi versus dpi. Let’s look at “ppi resolution.”
Resolution for Digital Devices
Typically, 72 or 92 ppi resolution (pixels per inch) is used for digital devices, and most importantly, at the size the image will appear on a digital device.
When people ask what does resolution mean, they also ask about 72 ppi resolution, or 92, or 300 ppi. This can apply not only to book production, but also to the size the image needs to be to appear on digital devices for web pages, in posts or social media. We don’t want images that are are too high in resolution, as it slows loading time, and it not necessary.
Resolution for Book Printing on Press
The resolution for printing in 300 pixels per inch, and at the approximate dimensions that the image will be when printed.
The resolution for printing in 300 pixels per inch, and at the approximate dimensions that the image will be when printed. We ask our clients to provide images at 300 ppi resolution for book printing. But, there is another important measure that is often overlooked. While the image must be 300 ppi or greater, and it also must be at the size it will be when printed in the book. It can be larger.
We can use any size image, but it will print at 300 ppi resolution on press. It doesn’t need to be exact. In fact, if the images are too large in dimension and too high in resolution, it makes them cumbersome to work with when designing a book, but it is not a problem when printing.
Increasing resolution is a mistake.
There is no substitute for the original image as taken digitally or scanned. Do not artificially increase ppi resolution, even if Photoshop allows you to do it!
One of the biggest mistakes made is increasing the resolution in Adobe Photoshop. You can do it, but don’t. Why? Because Photoshop can’t create resolution in images that doesn’t exist. Instead, they compensate by pulling a little bit of image from surrounding pixels. The result is muddy or out of focus. If you need to increase resolution, go back to the original image to see if you have a higher resolution version. Remember to check dimensions too.
Effective resolution explained.
We’ve designed books where original images were only 72 ppi resolution. Now, how can that work for 300 ppi resolution printing? It does work, because the images were 35 inches wide! They only needed to be a few inches wide on the printed page. By reducing them, we arrived at a acceptable effective resolution.
See how we switch from pixels to inches in this example in Photoshop.
Either get out your calculator and do the math, or check out the Effective resolution in InDesign and the size in Photoshop.
Notice in this stock photo example, that the image size in Photoshop is 3.75 inches x 2.5 inches, or 900 x 600 pixels. (Just change “Inches” to “Pixels”.) It is 240 ppi resolution. To view in Photoshop, select Image > Image Size. This tells us that the image is too big for online, at that resolution, so you would need to adjust it. It looks like it would be pretty small if printed in a book.
Look at the InDesign page …
Let’s hop over to our book layout in InDesign for a better look at answering the question, “What does resolution mean?” The page size is 11 inches x 11 inches in this example. The image dimensions are 3.75 inches x 2.5 inches. We placed the image and then we see how small it is when reduced to an acceptable effective resolution. The resolution changes to 302 ppi resolution, or ppi.
The solution may be to buy a larger image size if using stock photos, or to go back to your original image and see if you have a higher resolution version for the desired size when printed.
Here is what we see in InDesign. The actual 240 ppi resolution, and the 332 effective ppi resolution.
The effective resolution is arrived at by the image being enlarged or reduced. Increase a low res image in size, and you get an even lower resolution image.
On the other hand, used that same low resolution image and decrease the size, and the result is an increase in resolution.
also, you might wonder about the feature image background. When it comes to printing, the top half of the background is a representation of the dots or pixels in an image. The bottom half of the background is comprised of “rosettes” for process color printing. Look closely at any color photograph in a book, and you will se the CMYK process color rosette.
What does resolution mean and pixels to inches? How about ppi resolution? Have we answered your questions? Let us know if you have more questions! Get a book printing quote!
