Re: PIC32MZ Harmony Image Resizing/Scaling
This is a rather open-ended question. A lot of it is determined by image resolution, color depth and compression and how you wish to store the image (onboard or offboard NVM ). The largest internal flash version of the MZ EF is only 2 MB in size.
The Image Asset Manager within Harmony Composer will let you import the image and massage it to a format that should allow the MZ EF to render it. You will be able to modify the image using features such as cropping, resizing, adjusting color depth, or using compression or not.
Reduction in color depth goes a long way towards reducing the image size. On an MZ EF, the image really should be 16-bit RGB565 or lower anyway. One option is to store the image as raw pixels. The graphics library also supports Run Length Encoding (RLE) and runtime JPEG decoding. JPEG does a better job at file size reduction with photo-realistic images, while RLE does almost as good a job with images that has a lot of pixels in horizontal of the same color. However, decoding the image into the frame buffer takes time and you may get undesirable panning as the image is rendered on screen.
Storing on external NVM also puts a toll on image rendering time.
These are all factors you need to consider.