Here are the most common reasons:

• Image quality is too low
  • Will look pixelated or blurry
  • Will appear too dark
  • Will appear washed out (colors too light)
• Image is too complex
  • Parts of the image may not be produced
  • Contains color gradients
• Font is inadequate
  • Letters will run together and be hard to read
  • Letters will be illegible against the background
  • Font is too complex