LittleCMS Color Translator
For years Marti Maria is know of his excellent work on the free Color Engine LittleCMS. Recently he made a nifty application called: Color Translator. It’s the definitive tool for convert, assign and embed ICC profiles in TIFF, JPEG and PNG images. A must have for any color management pro.
If you work in any type of media production (print, website creation, 3D etc) this is a very important application.
Lately tested with my good friend Gerardo Estrada the Color Translator application succesfully in a HDRI workflow. More info please see below.
Download LittleCMS Color Translator demo
Note: The demo is limited to a fixed set of images (included), but all conversion features are fully functional.
Example usage of Color Translator in a HDRI workflow
You have a HDRI that was created with source files that are shot with a Nikon D300 with aRGB profile. So you have aRGB JPG source file ( aRGB has as you perhaps know a larger color range then sRGB)
In the free DS360_3DWorld_11 download package (more info please see here ) you will find the following HDRI panorama’s
a) a 11k .hdr based on sRGB primaries that is used for generating the sIBL HDR set – so for regular usage in sRGB range.
b) a 11k .exr based on aRGB primaries that can be used by users who need to get advantage of a wider color range.
Note you need to buy Color Translator before you can test the workflow mentioned below.
ps The 75% discount deal is discontinued
Extra note:the workflow below is made with Photomatix, Photoshop & Color Translator 1. PTGUIPro is also mentioned but for the color conversion specifically we just need Photoshop and Color Translator. Soon will make a new workflow made with the latest Color Translator 2. We need to test it because 2 has OpenEXR suppot so most likely we can skip the Photoshop part and do the whole conversion with Color Translator 2! The same process as described below is the same as with version 2.
This file was made by first generating a exr of every corner – with the aRGB source files – of the panorama with Photomatix wit the flowing settings:
Then generated the panorama with PTGUIPro
We now have a full panorama (.exr) with a aRGB based profile (but not visible we have to assign it in Photoshop we will see that later in the process below)
2) Now we are going to convert the EXR file in Photoshop into a linear 32-bpc TIF.
a) Color settings Photoshop:
b) Assigning the default Adobe RGB (1998) profile – on a 32-bpc image, Photoshop will use a linear version of the assigned profile automatically.
c) Saving as aRGB linear 32-bpc TIF file:
3) Install the Color Profiles for Color Translator
The needed profiles for this work can be downloaded here.
You need to install these profiles in your Color profile folder. A very good manual how to do that on your platform just have a look here.
When opening Color Translator you see at the Input & out put tab on the right a black folder (please see screenshots below) just click on it and select your Color Profiles folder as mentioned above.
Now we are going to use Translator to convert to Linear sRGB (D65):
Default input tab
Be sure you have the default RGB space set to the Linear Adobe RGB (D65) – we just installed
Be sure you have the destination space set to the Linear sRGB IEC61966-2.1 (D65) – we just installed
In this specific case we keep the Pixel Depth set to default “Keep Original Depth”
The output is now a linear sRGB (D65) FP 32 bit Tiff file that can be saved as a .hdr or .exr with Photoshop. Note that .hdr files cannot store profile but the image is sRGB (D65) based. So when opening in Photoshop you simply assign the sRGB profile (photoshop automatically assigns the correct linear profile).
The sRGB version panorama can be used for generating your own sIBL sets + tonemapping.
Many thanks to Marti Maria ( LittleCMS ) & specially Gerardo Estrada who helped with the workflow research!
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