Adobe Photoshop's functions for creating filled objects are producing different color output values while using the same color input value.

Photoshop stores different histogram index values (0–255) and that results in different tonal values (0–100%). Depending on the CMYK output process this bug may cause visible color differences.

These differences were primarily mentioned by Klaus Karcher in the German ECI mailing list during a discussion about rounding differences in TIFF based measurement targets.

Example

Different output values of different fill functions using 70% cyan as input value:

• Adobe Photoshop CS3 (Windows)
  
  • Fill: 70,2%
  • Paint Bucket: 69,8%
  • Fill layer: 70,2%
  • Vector object: 70,2%
  • Vector file: 69,8%
• Adobe Photoshop CS3 (Mac)
  
  • Fill: 70,2%
  • Paint Bucket: 69,4%
  • Fill layer: 70,2%
  • Vector object: 70,2%
  • Vector file: 69,8%

See Google Spreadsheet: Comparison between platforms and fill functions for more values.

Details

Affected functions:

• Edit > Fill
• Paint Bucket
• Fill layer
• Shape
• Vector file (imported)

Tested versions:

• Windows
  • Adobe Photoshop CS2
  • Adobe Photoshop CS3
  • Adobe Photoshop CS4
    

• Mac
  • Adobe Photoshop CS3
  • Adobe Photoshop CS4

Status:

• Reported: Yes.
• Replied: Yes, known bug.
• Fixed: Not yet, no ETA statement.

Workaround

To get always the same color value, you have to stick to one fill function. But there will be still a difference to imported vector files.

If you are experienced enough, it would be also possible to edit the index values in Photoshop or the generated pixel based file (e.g. TIFF).

Links

• Klaus Karcher: [ECI] Rundungsfehler in Testcharts (German; you have to be a registered member of ECI's “German language mailing list [ECI]”)
• Adobe Forums: Inconsistent tonal values across different Photoshop functions
• Google Spreadsheet: Comparison between platforms and fill functions

Comments

1. UPDATE

   Adobe Photoshop CS4 is also affected by this bug. CS4 acts like CS3, there is still a big difference between Windows and Mac version.

   The spreadsheet has been updated for CS4: http://spreadsheets.google.com/ccc?key=pdbV5FYYycngGI-oeBuGcKw

   — Frank Spangenberg at October 27, 2008 [#]