SquishPic uses three different terms for outputting an image:
When you open and modify a SID image, use File > Save to update the current SID image file, or use File > Save As to save a copy of it.
If you open an MG2 or MG3 format image, saving will create an MG4 image with an opaque alpha channel.
Saving uses the same compression ratio as the original file.
Use Compress Image to convert another kind of image to a SID image.
You’ll be prompted to set the output image compression.
Compressing requires a data plan. Learn more.
You can specify the default compression settings in Preferences.
Use Decompress Image to convert a SID image to a JPEG, PNG, or TIFF file. JPEG files will be saved using approximately a 7:1 compression ratio; PNG and TIFF files will be uncompressed.
You can set the default file format for decompressing in Preferences.