Re: Setting up HP DreamColor LP2480zx monitor for work in Color

Hello Rich,

I just read your comment on the calibration software and I wanted to clear up some misconseptions that you might have. I was on the ObiWan design team and the data path on this display is quite different from any other display. Unlike many of the displays that you are used to working with, this display does not have a typical LUT structure and it was not aimed at the typical graphic arts professional or photographer. The display does not have traditional RGB gains. The display has adjustable color space and this puts some rather stiff constraints on the use of look tables. The display has a built in matrix shaper lut configuration. This consists of an input lut, 3X3 hardware multiplier and an output lut as well as a scalable white point. The first look up table, must, by definition be the canonical transfer function of the color space. If it is not, the 3/x3 multiply will introduce large color errors due to the non-linearity. The white point setting is a function both of the matrix multiply and the backlight adjustment. There is no independent control of backlight RGB. The multiplying matrix is a trim factor for white and it sets the primary mappaing. The second LUT must correct the display color drift and it must, again by definition, be the inverse of the display Optical transfer function. While you might have certain preferences for display calibration software, the typical functions that you desire cannot easily be employed in this display pipeline. If you wanted L* mapping in the display, you would have to make sure your graphics card generated the output in L* form. This means you would be putting a LUT in front of a LUT. You would quantize your out put to the display. The only thing that I wish I could have added in the display pipeline was an offset to lower the display contrast ratio.

The application features that you desire that are found in the other apps that use RGB gains and LUTs are not really implementable in this display.

I personally use this display in an ADOBE RGB workflow with the display set to ADOBE_RGB and the full X-rite profile applied. In photoshop, this gives the best display / print correspondence that I have ever encountered. The display correspondence in a non color managed workflow using ADOBE RGB and my Epson printer set to ADOBE RGB, the display to print matching is limited by the 1000:1 contrast ratio of the display. This is why I would like to be able to implement a brightness adjustment.

I hope this clears up some misunderstandings, but if you want to talk off the forum, contact me at tlianza at xrite dot com.

Happy new year,
Tom