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mgts24

White balance and color space issues

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Hello,

 

When viewing a file in RTI viewer recently, I noticed that there was an overall bluish color cast to the image (object and bacground were fairly neutral: see attached files). The original RAW captures were created in the sRGB space using Canon's 'flash' WB setting, and the jpegs exported to RTI builder were in sRGB.  Oddly, snapshots exported from RTI Viewer seem to revert, more or less, to the 'as shot' WB.

 

Anyone have any idea what might be going on? 

 

The upper photo is the 'blue' screen grab from the Viewer, the other is a jpeg from an original RAW file.  By the way, the screen grab is from a recently calibrated Mac Book Pro.

 

post-598-0-10491700-1435155190_thumb.jpg

 

 

post-598-0-16184900-1435155191_thumb.jpg

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I'm not sure exactly what is going on, but I have a couple of questions.  What type of RTI?  i.e. lrgb PTM, rgb PTM or HSH?  The lrgb PTM is the most prone to color shifts, usually rendering shiny surfaces as green, for example.  Though I haven't seen this blueish color you are showing here.

 

The other question is whether you were applying any rendering modes?  The diffuse gain rendering mode can create false color areas - though again, it doesn't usually look like this.

 

I also want to understand the "snapshot" from the viewer's tools, vs the screen grab you are showing here.  The snapshot is calculated when you press the snapshot button, so it may be something to do with your graphics card and how it is displaying the data in the viewer, vs the calculated image you see in the snapshot. Can you post a snapshot as well?  Other than the above mentioned color issues, I haven't seen what you are talking about.  So this is speculation

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It's an HSH file.  I went this route because this object has very shiny surfaces.  In fact this file displays in the main window with the strong blue cast immediately on opening, i.e., in default mode.  What's odd is that the colour is much more true in the navigation/bookmarks window, that is, not bluish.  Also, while my screen grab (using Apple Grab app) is blue, the snapshots exported using the tools seem ok (I have attached one below).

 

So, to summarise, the blue cast is exhibited in the main window of Viewer for an HSH file, but not the smaller navigation/bookmarks window.  The blue cast is not retained in snapshots created by the tools of viewer.

 

Here is a snapshot of the image created with the Viewer tools:

 

post-598-0-80651500-1435260391_thumb.jpg

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In order to be sure, if you save a snapshot with the tool of the viewer the image has the right color but the main window shows the problem.

Do you have the possibility to share with us the RTI file? It can be very important to understand where is the problem. 

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Hi Gianpaolo,  That's right.  The problem seems to be with the main viewer.  I can upload the RTI file, but it's 139 MB, and that doesn't seem to be allowed.

 

Michael

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We have limited space on this hosted forum site, but I've set up a dropbox where Michael can put it and Gianpaolo can pick it up.  I'm emailing the link to Michael and Gianpaolo. If the data is too sensitive for that - then maybe you can both figure out another way to get the file to Gianpaolo.

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I have tested the file but I'm not able to find a computer to reproduce the problem. All computers that I tested show the image correctly. What are the features of your computer (CPU and GPU)?  

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I tried this on my iMac running OS 10.9.5 and didn't see a color shift.  The navigator window looks the same color as the image in the main window.  Makes me wonder about your GPU - but that's more for Gianpaolo to say than for me!

 

Carla

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