topic Re: Existing internal processing and adjustmentusing RAW format in EOS DSLR & Mirrorless Cameras

Existing internal processing and adjustmentusing RAW format

giladweil — Thu, 31 Jul 2014 06:45:05 GMT

As part of a vegetation monitoring program in nature reserves, I examine changes by using a time series of photos. I use a modified rebel i3, in which the internal IR filter has been removed (http://www.maxmax.com/ircameraconversions.htm). I use a series of external filets in order to sample in different wavelength. I use fixed WB, shutter speed and RAW format only.

I dont need a "good looking" picture - I need the original data with minimal Intervention of the camera.

But my question has to do with the image processing – since the results I get aren't good enough:

I am interested in the raw values of the radiation – Is there any additional processing in RAW format, such as balancing blue green and red, or adjustment in the case of saturation of the sensor?
Where can I find quantitative data (not picture) about the behavior of the sensor along the spectrum?

Thanks!

Gilad Weil

Remote Sensing,

Nature and Park Authority

Re: Existing internal processing and adjustmentusing RAW format

Skirball — Thu, 31 Jul 2014 14:41:44 GMT

It sounds like you're looking for the raw data (not to be confused with RAW files) coming off the sensor. Perhaps someone here happens to know of something, but you're looking for something well outside the digital photographers use. The software that we use is designed to do the opposite. Photographers don't care about the individual data, only how it comes together for the final image, and how we can manipulate those values into a more pleasing image. You're not looking for standard digital photography editing software, you need something designed to get at the raw data.

The camera's histogram is basically a bar graph showing combined relative intensity of 256 tonal values of grey across the photo. Which is in a sense what it seems you're looking for, however, this is far from data. It's only representative of the final image, processed through the camera's settings, and limited to the range of what an 8-bit image can display. IT's not really showing you what's coming off the sensor.

Manipulating a RAW file in post would be guess work. You could increase or decrease the intensity of any part of the spectrum, but it doesn't mean that's representative of what hit the sensor. It sounds like you want the information preprocessing. I'm sure there's software out there somewhere, as people use this kind of stuff to compare sensors and whatnot; but you're average photographer has no experience or need of such software. If nobody here happens to have a clue I suggest you go to Canon Rumors.com, there are several extremely knowledgeable folks over there that might be able to point you in the right direction. Good luck.

Re: Existing internal processing and adjustmentusing RAW format

ebiggs1 — Sat, 02 Aug 2014 02:16:09 GMT

As you probably know there is not many adjustments done to a RAW file by the camera. Hence the term RAW file.

Software like ACR (Adobe Camera RAW) is needed. Can't you do whatever adjustments you need with it?

RAW files the camera creates have a header file which contains all of the camera settings, including sharpening level, contrast and saturation settings, colour temperature and white balance, and so on. The image is not changed by these settings, they are simply tagged onto the RAW image data.

The RAW image data, what the sensor saw along with that data is now saved to the card.