[Radiance-general] Reflectance meausrement using macbethcal utility

[Greg Ward]

It's all explained (as best I can) in the macbethcal man page:

	http://radsite.lbl.gov/radiance/man_html/macbethcal.1.html

You give it an HDR file of a Macbeth color checker chart under uniform illumination, and identify the chart corners in the image.  From that, it creates a color mapping file you can use with pcomb to correct the image.

However, it does not work very well for digital cameras.  You are much better off converting the RAW files directly using Dave Coffin's dcraw, which you can find on the web.  Getting to reflectance is more difficult, and depends on your situation.

Check out the following if you haven't already:

	http://radsite.lbl.gov/radiance/refer/sg96crs.pdf

Cheers,
-Greg

> From: Jia Hu <hujia06 at gmail.com>
> Subject: [Radiance-general] Reflectance meausrement using macbethcal utility
> Date: July 29, 2014 8:22:08 PM PDT
> 
> Hello,
> 
> I am using Radiance macbethcal to estimate the material reflectance.  If I get the calibrated HDR image, how could I determine the RGB/reflectance?   Should  I pick a point in the generated HDR image to retrieve the RGB values, and then directly set the RGB to material RGB in Radiance? 
>  Is there any Radiance tool to directly obtain RGB value of a given pixel? 
> 
> Thanks,
> Jia