The problem is I probably don’t have enough technical understanding about how to get all the data from the cr2 file out of raw therapee.
I would like to get a 16bit fp exr file - I reset everything, no tonemapping, linear curve, no nothing and just save it as linear exr file - that would be great.
I just don’t see how all the linear information could be stored in a 16bit tiff file.
I have sun in my image for example, I can see, there is more information if I exposure down, but the information is gone when I save it as 16bit tiff - obviously I would say. And converting that to linear exr using inverse srgb gamma for example will not get the values back.
So is there a way to get linear images out of therapee? Sorry for my ignorance thank you
I don’t know your camera or your selected raw format, but the original image was likely encoded as 14-bit unsigned integers by the camera, so a 16-bit unsigned integer TIFF has plenty of “room” for the original information.
I’m just guessing here, but if you’ve turned off all the RT processing, the only place I can surmise such information loss is in the color/tone conversion when the TIFF is saved. Evidence of that would be an ICC profile embedded in the TIFF that contains a non-linear tone curve. If you want a true “linear” export file, TIFF or OpenEXR, save it with a linear ICC profile conversion, in the case of RT, select one of the profiles with a gamma = 1.0.
Of course I thought about linear-encoded ACES P1.
Have you tried using the unclipped pp3 profile bundled with RT? I think its purpose is precisely what it says, though I don’t know if its output color profile is linear…
Yeah I tried that one, but doesn’t really do much else than what I’m already doing…this is kind of my starting point. Still not solving the highlights clipping issue.
It all looks like RT is just ignoring information above 1. Or lets say above 100%
I can see it on the histogram - the sun is just above 1 and to get it inside the histogram I would have to set the highlight compression to about 73, then it is sitting at 1.
Or I have to give RT some input profile or information about the camera/file that will map it correctly from the get go…not sure…
This is kind of an ongoing theme in a lot of software, that tries to deal with highlight above 1 from raw data - it is either called Highlight Compression or Highlight Recovery or Pink Highlights or whatever
The process is trying to “save” the information bleeding above 1 and “soft clip” it inside the the 0-1 brightness gamut
But thanks for the suggestions!
Hello, I dont think I must have a wider working profile, I dont think the primaries are what affects this situation, but sure, I can switch to adobe rgb or AP1, no problem. The tools settings have the same affect. And yes, I’m exporting with linear profile.
I think I’m starting to understand the issue. Yes you are right, there is nothing to do but recover highlights - that’s what I mean by lost information
And yes, you will get this clamped image when you dont have highlight reonstruction turned on.
And when you turn off clip out of gamut colors - you will see the pink cast
that pink cast doesnt mean there is no information
it means there is only partial information in only some channels
they dont all meet at 1, some of the channels continue above it but not uniformly, that’s why the pink cast
you can check the histogram and you can see as you move your cursor from the blue sky into the center of the sun - the sliders will leave the histogram
try these settings to see what I mean
this little sun is taking me through an information wormhole…
this is what I found - these articles on darktable go deep into the topic
there are actually couple of ways how to recover the highlights and every software deals with it it’s own way
but darktable probably gives you most options I guess - but as I said, sorry for my ignorance, I opened RT just now and started digging through this
too much info
if you search google for raw pink highlights or something like that, you get a lot of hits where people are dealing with this in different softwares
I loaded your raw in my hack software, where I can reliably look at the image data straight out of the file, and the sun’s pixels are basically piled up at the sensor saturation point, no relevant data there except to “make white”. There are a few pixels in the “star spikes” that start to show gradation, I assume that’s what you want to protect. But the center is just maxed out in all three channels.
Where the “pink” is made is when white balance multipliers are applied to the data of the three channels. In this case, since the saturated pixels have lost any gradation they might have had and all got piled up into the same value, the red and blue components get shifted according to the multipliers (green white balance is usually 1.0) and the new RGB values typically make “pink”, or properly, magenta. If you set the white point to the smallest maximum of the three channels, the pixels go back to white as the image data is clipped to that point for export. Inside good software that uses floating point data internally however, those values pushed past white are still there, as values > 1.0, which by convention is usually the floating point white point. Highlight “construction” can take some of that data and shift it back below 1.0, but now that’s made-up data. And your image really doesn’t have much to work with in the region of the sun.
Highlight construction can be helpful putting some definition back into regions of an image that were over-exposed. But if the region is a light source, I tend to just let that go to white oblivion. In the case of the sun, you’d have to screw on beaucoup neutral density filtration to get meaningful gradation, gradation you’re not seeing normally anyway…
After @ggbutcher, I would say that in the sun, there is nothing to recover as all information of the 3 channels is lost in the raw. At the border of the star, some channels get unclipped so using
highlight reconstruction (with highlight compression as usual) will pull back values to 1 at the center and rebuild some data at the border.(and RT is rather good at that).
There is nothing else that can improve the situation except some painting.
Got it, yes I was interested just in the imidiate area around the sun. I know there is nothing in the middle, that wasn’t my concern. And by now, it became more about learning what goes on behind the scenes technically, rather than visual issues. And yes, as I go more in RT, it is a great piece of software. Thanks!