Digital Photo Printing

Maximize Your Photo-Printer Clarity

What is the best PPI image setting for your printer -- 75, 100, 120, 150, 200, 300, ... ?
Download the CameraTrax PrinterTest image and find out! ... It's Free!

What does it measure about printed pixels?
  • Monochrome Resolution - How small before they blur together?
  • Color Resolution - Does color improve resolution?
  • Color Value Discrimination - Can I distinguish Cyan [0 231 255] from Cyan [0 239 255]?
Measurements:
1) Download the CTPrinterTest.TIF image.
2) Print the image [4x6-in at 600 PPI] on your photo paper.
3) View this print at the distance you will view your photo.
  • Monochrome / Color Resolution:
    • Blurred printed pixels mean the PPI is too high.
    • Blocky printed pixels mean the PPI is too low.
    • [Hint: The exact PPI value is not critical so pick a number which evenly divides into your printer's reolution -- eg. 1200 DPI / 200 PPI = 6].
  • Color Discrimination (at your selected PPI):
    • Look at the Cyan, Magenta, Yello and Grey arrays.
    • Find the Row that matches your selected PPI.
    • Find the Column square with a visible pattern.
    • Read the number at the bottom of the Column.
    • It is the smallest color value change you can visually detect at that PPI at the selected viewing distance. [eg. Cyan '24' would mean a change of 24 in the RGB Green value].


CTPrinterTest.TIF [25Mb]
Results:
  • The selected PPI is a good setting for printing your photos at that viewing distance.
  • Ideal print size is determined by your selected PPI and the pixel dimensions of your digital photo.
  • Color Discrimination does not mean the printed color is wrong; it just shows the printer's color resolution and human eye's color discrimination limits.
  • Note: Because printed color discrimination is usually not even close to a value of '1', the photo-printer remains the weakest link.

Print Sizes:

The following table shows the relationship between digital camera image size and photo-print size depending on the selected PPI. Note that:
  • You don't need a 10 MPix digital SLR to make nice looking 4x6 snapshots.
  • Some print sizes are very large -- but so are the viewing distances.
  • Printing a 10 MPix image on 13x19 paper and then viewing it from a few inches will definitly show pixelization. This is expected. The options are to print it smaller or stand further away.
  • Printing a 10 MPix image at 4x6 with 400 PPI is a waste of resolution because most printers cannot resolve 400 PPI and, at 8 inches viewing distance, the extra detail would be a blurr anyway.