Image resolution change is needed "for screens", that is, when posting your final artwork on social network websites, and "for print", that is, for printing your final artwork.
First of all, we are going to look at the resolution setting for screens.
From ① the Tool Selection window, select ② Canvas tool.
Select ① Resize.
Turn on ① Keep Aspect Ratio.
Resolution change for screens can be done by selecting ② Pixels.
For screens, you will be changing the pixel count (px), instead of dpi.
Change ③ the Width (px) from 768 to 50. Once you are done, tap on ④ ✓ to finish.
Setting the pixel count to a significantly lower resolution worsens the image quality.
If you decrease the pixel count, you will get more maximum layer limit. Once you reach your maximum layer, try decreasing the pixel count. Also, decreasing the size of the canvas can help you work faster, and make the files take up less space on your device. Now, you can adjust the size of the screen with pixel count (px), and not with dpi.
Next, we will cover resolution settings for printing.
For artwork you would like to print, you can change the canvas size in mm and resolution (dpi). Set the dpi to minimum 300 for clean printed results. Dpi refers to dots per inch (25.4mm).
※Caution: when requesting a printing shop to print your artwork, make sure to be aware of your dpi and size. It is extremely difficult to change the dpi afterwards.
Turn on ① Keep Aspect Ratio. Changing resolution for artwork to be printed can be done by first selecting ② Print.
In print, select dpi. Adjust ③ the dpi from 350 to 50.
Once you are done setting the new value, tap on ④ ✓ to finish.
Decreasing the dpi as shown will worsen the image quality.
Next, we will cover reduction calculation method.
Turn on ① Keep Aspect Ratio. Set the size: ② Width(px) from 768 to 150.
Tap ③ Linear, to select a calculation method from Sampling, Linear, and Trilinear.
This is a comparison image.
From the left, the quality changes from low to medium to high. Normally, we suggest choosing Trilinear (since Trilinear uses hardware functions, it may not be applicable in some devices).
Next, we will cover magnification calculation method.
Turn on ① Keep Aspect Ratio. Set the size: ② Width (px) from 50 to 1,500. Tap ③ Linear, and choose a calculation method from Nearest Neighbor and Linear.
Here is an image quality comparison between canvases processed by Nearest Neighbor and Linear. Normally, it's better to choose Linear.