OpenEXR file format output

Hello, I was searching the forums and documentation and I couldn’t find a way to export exrs from the queue.
Was exr at one point a part of the output formats and is no more?
I found exr mentioned here, but it is probably obsolete
http://rawpedia.rawtherapee.com/Image_file_formats_and_compression#OpenEXR_16-bit_floating-point

Was exr replaced by TIFF float?
It would be very helpful to have a direct exr output, because the float TIFF for some reason looks all kinds of wrong.

Thanks a lot

On the same page you are referring to it says, that the images can be converted externally to other more efficient formats, such as 16-bit JPEG-2000 or OpenEXR.

http://rawpedia.rawtherapee.com/Image_file_formats_and_compression#Final_format

The place you are referring to just compares the file sizes.

Got it.
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 :slight_smile: 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.

https://rawpedia.rawtherapee.com/Color_Management#Output_Profile

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The camera is CANON EOS 80D
I think I have reset everything I can think of
The tone curves are linear

nothing in tonemapping

and this is my output profile
image
I didnt find the exact ones with the linear gamma as in the link you’ve sent - probably renamed by now?
but I created a new one like this
image
so I hope it’s ok

the problem is still the same
there is a sun in my image
and this is how RT is showing it, this is how it’s exported in the tiff file basically
image
and when I exposure down slightly, I can see there is more information there
image
the only way to get the information and not touch overall exposure is to use some Highlight Compression

but that seems to me like I’m destroying the linearity of the light and I should not have to do that, no?

thanks a lot for your time and answers! :slight_smile:

this is my cr2 file if you would like to take a look at it
_MG_1547.CR2 (27.6 MB)

I’m not color expert at all, but I would have used something bigger than sRGB. Maybe ACES P1?

Sure, I can use that, but in this case I don’t care about color gamut, I just need it to be linear. So linear srgb if fine for now.

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! :slight_smile:

Heve you tried tweaking the raw white points in either the raw tab in RT, or in the camconst file?

In my opinion you must use a wider working profile, and then export to a linear profile.

In any case, you may wish to deactivate the Clip out-of-gamut colors option inside the Exposure tool, or you will loose any information outside the color space you’re using.

However, I can’t see the lost information you talk about:

This is the image as loaded:
_MG_1547

And now with an exposure compensation of -1.0:
_MG_1547-1

That sun is definitely clipped at raw level, so nothing to do there but recover highlights.

As a matter of fact, those images where with Clip out-of-gamut colors turned on. This is how your image looks with the option turned off:

_MG_1547-2
Aside from the pink cast, there’s no new information there.

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

but

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


and then try the hl compression at 74 - it will not be 100%, but you can see the sliders get back and the light around the sun get a little bit more information inside

this little sun is taking me through an information wormhole… :slight_smile:

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

more info

too much info :slight_smile:

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…

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Got it! Thanks very much for the insight and the explanation. I shall stop here and let the data go to white oblivion :smiley:
cheers

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.

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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!

But back to the topic, any chance of getting OpenEXR file output straight out of RT?