Image Resolution Question

I had a question about resolution in KaleidoPaint this morning (reprinted below). If KP exports at 72 DPI, how do you get a good quality print, let’s say 300 DPI?

An excellent question, and one concept that is not easily understood. But once you get it, it will stick with you for your whole artist’s career.

72 dpi is the standard resolution for exported digital images. That means 72 pixels of colour information, per inch, when displayed on a screen. Sometimes we see 96 dpi. If you walk close to a tv screen or computer monitor, and peer at the surface, you can actually see the pixels, tiny squares of red, green and blue (RGB).

Getting the correct print resolution is a matter of grouping the existing pixel information differently inside your image file. That’s called resolution or ppi, interchanged to dpi for the print industry. Pixels per inch or dots per inch.

Let’s take an easy number for an image size: 7200 x 7200 pixels, a square image.
If the resolution is 72 dpi and you print it at that resolution, your print will be 100 inches wide. Easy math.
If you change the resolution to 144 dpi, double of 72, then it will print at 50 inches wide.
If we double again to 288 dpi, then it will print at 25 inches. Which is an excellent number of pixels or dots per inch, for a paper print.
The file has the same number of pixels in width and height, but it is sampled differently.

Have a look at the three images below. The number of pixels remains the same, but the resolution is changed and the size of the print changes at the same time. The “resample image checkbox is NOT CHECKED. The pixel dimensions remain the same.

The trick is to change the grouping of your pixels without changing the number of pixels. You don’t want to delete or invent pixels, only regroup them differently. I.e., change the resolution.

The higher the DPI the better your print quality.

With the new KaleidoPaint, the tiles exported can be anywhere from 256 pixels up to 4096 pixels square.
Likewise, if you save an image of your drawing, the resolution remains 72dpi but the dimensions change, depending on the size you choose.

In order to change the resolution, you’ll need to open your drawing in a pixel-based application like Photoshop, and futz around in the image size section. Again, make sure not to delete or invent pixels, only change the dpi. You’ll need to play around with the options in there to make sure of that.

I usually export a tile of my drawing from KaleidoPaint, because I like to recolour my characters so they can be differentiated from each other. Different colour clothing etc. With the 4096 tile, I end up with way more information than needed. A resolution of 700 dpi for a small 16×20 print was a big surprise.

700 dpi for 16 inches wide = 11,200 pixels of information in its width.
You could resample this to print it on a huge canvas, at 150 dpi it would be 74 inches wide!

Changing the resolution of an image without changing the number of pixels affects the dimension of the final print’s size.

Hopefully clearer for you now. Lots of articles on the web, I’m sure you can find.



P.s., I’m not the KaleidoPaint app developer, only a ten yearlong fanatical user!
Jeff Weeks is the app’s creator.

On 2022-12-26 3:38 a.m., Ariella wrote:


I would like to use my projects made in your application to print materials, however, I have some questions about export quality.
When designing and exporting the images in Kaleido Painting, I noticed that they are made in 72dpi, even when I am using the best quality available. As far as I know, to print products, the final image must be at least 150dpi (300dpi, if possible). So, is there a way to export a project with at least 150dpi using Kaleido Painting? Or is it safe to use 72dpi files for printing purposes? Thank you very much. I’ll be waiting for your feedback.


I’ve written about image resolution before on my other blog about PowerPoint. A discussion of raster images vs. vector images if you’re interested in reading: Image Resolution Part 1: vector vs. raster

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