If you are looking to resize images, this article should be useful.
For more information on changing canvas and resolution, check out this article: Setting the maximum canvas size for printing
Resizing an image in Sketchbook Pro for desktop
Use Image > Image size to change the dimensions of the image in pixels, its resolution, or the document size.
This change directly affects memory usage, quadrupling it if you double the pixel size. Due to memory requirements, there is a 8192 x 8192-pixel upper limit on image size for the 64-bit version.
Resizing an image
- In the toolbar, select Image > Image size.
- In the Image Size window, do any of the following:
- To change the pixel size of the image, in Pixel Dimensions, choose between pixels or percent, then enter a numeric value for Width and Height.
- To change the file size, in Document Size, choose the units (percent, pixels, inches, cm, or mm), then enter a numeric value for Width and Height.
- To change the resolution of the image (leaving the document size the same, but increasing the quality of the image and resolution), in Resolution, choose from pixels/inch, pixels/cm, or pixels/mm.
CAUTION: Increasing the resolution increases the memory size of your file.
- Tap OK.