Generally, if people submit misrepresentational previews of their Bootskins we will reject them.
A preview should be an honest and fair indication of what the Bootskin really is....in other words it MUST be a 4bit [16 colour] image saved as a jpg for upload.
That will then naturally be 'full colour' but if re-dithered to 16 colour it 'should not' then be lossy.
If you find any that are 'cheating' let us know and they will be removed and the uploader emailed to submit a more 'accurate' preview.
Reason is it's unfair to those who are honestly depicting their 'work'....