Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: billthecat on June 26, 2015, 07:34:07 pm

Title: How to add yellow - making color wheel RGB and perhaps yellow
Post by: billthecat on June 26, 2015, 07:34:07 pm

Hello,

I've made a color wheel to take better photos. It fits in front of a lens. I've been using it for red, green and blue, and it works well for that. Combining the colors works well as they are RGB and I have the channels for that.

But I thought that I'd add yellow to the red, green ad blue, but I'm not sure how to combine yellow into the mix. If anyone has any information you can let me know.

Thanks!
Bill

Title: Re: How to add yellow - making color wheel RGB and perhaps yellow
Post by: Jim Kasson on June 26, 2015, 07:43:58 pm

Quote from: billthecat on June 26, 2015, 07:34:07 pm

I've made a color wheel to take better photos. It fits in front of a lens. I've been using it for red, green and blue, and it works well for that. Combining the colors works well as they are RGB and I have the channels for that.

But I thought that I'd add yellow to the red, green ad blue, but I'm not sure how to combine yellow into the mix. If anyone has any information you can let me know.

I assume your sensor is monochromatic. If so, what you're doing if you add a yellow section to your wheel falls under the category of multispectral image capture. There are many papers on how to convert multispectral captures to RGB color spaces, and the results can be more accurate than three-filter captures.

Here are a few papers to get you started:

http://guchi.gsic.titech.ac.jp/NV/SPIE4663-04.pdf

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=920567

http://www.colorlab.no/colourlab_old/research/multispectral_image_capture

There are many more. You will have to dust off your linear algebra skills.

Maybe someone has written a program to process multispectral images into tristimulus values based upon arbitrary filter responses, but I don't know of one.

Jim

Title: Re: How to add yellow - making color wheel RGB and perhaps yellow
Post by: billthecat on June 26, 2015, 11:13:30 pm

Jim,

Thanks for the links. It seems to be pointing me in the right direction.

I might have found some software to help:
http://rsb.info.nih.gov/ij/docs/guide/146-9.html#toc-Section-9

Bill