4 Replies Latest reply on May 8, 2015 12:24 PM by Chris Tarantino

    correctly converting 32bit cg render passes layers to 8bit


      This topic is related to creating render passes for images rendered using 3d cg applications.

      These render passes are often shading components like diffuse,reflection, specular etc.

      Most current 3d cg rendering pipelines use a linear light workflow where the output is best saved as float file format

      which provides a significant color fidelity advantage. My preferred output format is openexr.

      When these files are opened in photoshop the image is in 32bit mode.

      These render pass layers need to be blended with lineardodge(which means add) in order for the result to look like the beauty render.

      Float 32bit photoshop images are much larger than their 8bit counterparts.

      For this reason often it is desirable to convert to 8bit.

      Most users set there color workspace profile to adobergb or srgb.

      With the one of the above icc profiles and the default photoshop preferences, converting a image with lineardodge layers from 32bit to 8bit causes a dramatic change in the result.

      To fix this we need a linear icc profile to convince the conversion to create a 8bit image that looks just like the 32bit image.

      Before you convert to 8 bit load your linear icc profile under edit->color settings.

      After the image is 8bit load your preferred icc profile and continue working.


      The link below very nicely describes how to create a linear icc profile



      I dont see how to attach a specific file in this forum so at this parrallel cross post on cgtalk

      you can find an linearadobergb icc file attachment.