Chronos > Software Dev
Missing (weak) Green colours
A.Angelov:
Hello,
I have noticed that the camera has hard time capturing properly green objects (it is shifting only the greens toward the yellow colour)
I was wondering if this is an issue with the IR filter that is just in front of the sensor or with the sensor itself.
Do you have any good suggestions to fix it?
Thank you!
PS: The problem more likely is not related to the lighting because I am using high quality CRI (colour rendering index) diodes and it also happens during sunlight shooting
tesla500:
Hi A.,
Could you post an image to show the issue? If you have a comparison with an image with proper color that would help as well.
David
A.Angelov:
Hi David!
First of all, please excuse me for the slow reply.
I just made a compilation of a shot taken with a standard DSLR camera a (lumix fz1000) and the Chronos 1.4.
https://drive.google.com/file/d/0Bz3D_Jwk70plZnRCNDFCcThZTkE/view?usp=sharing
https://drive.google.com/file/d/0Bz3D_Jwk70plUTV5QUUtVUFoTUU/view?usp=sharing
Several considerations must be done first: .
I used a high quality light (CRI of 95) for both shots in order to eliminate light source as the possible origin of the problem.
Also, i made a white balance on both cameras just before taking the pictures.
The first photo is of the lumix, second is of the Chronos without any corrections and third is of the same second picture with an exposure and whitebalance correction.
The left photo is taken with the Lumix and the colors are pretty much the same as the human eye can see.
The "problem" is that one of the green colors (the one marked in red elipse) is somewhat different from the green colour captured by the lumix.
I know it doesnt seems as much of a deal on that particular example, but this problem is much more visible outdoor with sunlight as source. Here is an example:
https://drive.google.com/file/d/0Bz3D_Jwk70plbGdiNEQ5SW0zdTQ/view?usp=sharing
I am sorry i did not took a picture with the Lumix camera but I am sure the grass was way more green. It was very fresh and in the shot it seems very old almost burn from the sun.
Hope this two examples can serve you as a reference.
By the way, I have 4 ideas of what might be the problem:
1) The sensor that Chronos uses has dificulties capturing this particular wavelength
2) Mi sensor in particular happens to be a bit "bad"
3) The IR filter in front of the sensor is causing part of the problem (i could not dismount it in order to make a test shot without it)
4) The problem might be caused by saving the shot with the standard "0.70" pixel bitrate instead on something higher.
Best regards and thank you for the constant help.
AimedResearch:
I doubt the sensor is lacking in sensitivity for green. I believe it is common for sensors to be most sensitive to red, green, then blue the least. Its not drastic, maybe a few percent in terms of quantum efficiency (I didn't look into the response of the sensor, I am guessing from what I've seen on other HS cameras). I would suspect the optical components starting with the IR filter down to the lens. I recently was playing around with different IR/UV cut filters for the Fastec TS3. The results of different IR/UV filters (behind the lens), is wild. Remember, your lens is not designed to pass IR and UV. It is designed to pass visible light. Those wavelengths will focus at different points. If you focus on a subject using visible light and change to a UV light, the focus will be off. The sensor doesn't know what wavelength excites each pixel. Only after filtering and digital processing is the color interpreted. My experience is that high-speed cameras do not have enough native color saturation. With expensive high-speed cameras, even if you get the color balance right, the color is never brilliant enough.
A.Angelov:
Thank you for the very interesting information AimedResearch!
Appreciate sharing your experience
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