(new) features unexplained in Rawpedia?

Just trying to keep up with the wonderful progress of RT development. Two questions (which Rawpedia leaves unanswered):

The downloads page in blog shows: “RT 5.4 for Appimage 64 bit fast”
How does this version differ from "RT 5.4 for Windows Vista7/8/10 64 bit fast?
I have seen other references to “Appimage” elsewhere. To what does it refer?

From Rawpedia:
"The default processing profile for raw files as of RawTherapee 5.4 is “Auto-Matched Curve - ISO Low”.
What is the purpose or intent of using this option as opposed to “Neutral” as the default processing profile for raw files?
I know I’m being a bit lazy here. I could just examine the respective pp3 files side by side and compare. But I would appreciate a bit of the rationale for the differences. What is being auto-matched to what?

Neutral means (almost) no processing. No RT tools are invoked.

Auto-Matched means RT builds (and uses) a tone curve which aims to match the jpeg file embedded in the raw file.

ping @Carmelo_DrRaw for RT appimage

thanks @heckflosse for your reply.

May I assume this means RT contains a variety of tone curves, and selects one appropriate to the camera in use? In constructing these tone curves, what assumptions are made about the embedded jpeg file (i.e. what adjustment has the camera made in creating the embedded jpeg?) How does this differ from creating a custom dcp file for the camera and selecting it under Color Management \ Input Profile \ Custom?

No, it compares the embedded jpeg to the raw and builds a curve. For details, please ask @agriggio. He coded that awesome stuff.

An AppImage is for the Linux desktop, if you’re using Windows or macOS, then it isn’t for you!

An AppImage basically statically links all necessary libraries into one (large) binary. A user on linux need only donwload the AppImage, chmod it, and run it. No need for dependencies. Other options similar-ish to AppImage are Flatpak and Snap.

Many thanks for your reply. I’m on Windows, so no worries/

Thanks @heckflosse.

Over to you @agriggio
Does this mean that RT builds the tone curve ‘on the fly’ ? And, what considerations are given to how the camera alters the raw data when creating the embedded jpeg?

Hi @mikesan,


No considerations to how it is done – we only look at the thumbnail, and more specificially, at the luminance values, to build a tone curve that gives a reasonable match for the overall “feel” of the pic. We don’t care about other stuff that the in-camera processor might do (lens corrections, sharpening, noise reduction, …).

1 Like


I forgot to reply about this one:

The input profile (dcp or icc) is mostly about the chromatic part (with the exception of the “tone curve” of dcp profiles – discussed below), so the two settings are complementary and work well in tandem, in fact.

dcp profiles can have an embedded “tone curve”, but that is a fixed, static curve designed by the dcp profile builder (in case of the profiles shipped by RT, they embed a generic “Adobe-like film curve”, which is the same for all cameras). Whether you like that better than the automatically-computed one is simply a matter of taste.

Finally, I should mention that some profiles are designed to work when applied to a specific tone curve, and might give poor results with other curves. Covering this is beyond the scope of the “auto-matched” functionality, but FWIW in these cases RT can first apply the tone curve of the profile (if the option is checked) and then adjusts it to match the embedded jpeg. The results in some cases are different than just matching without applying the embedded tone curve, but I can’t say “better” or “worse” – this is again a matter of taste.

HTH, and sorry for my sloppy terminology, I am far from an expert on colour.



Many thanks for your replies. Helpful.

Correct me if I am wrong, but this tool can allow for multiple results from the same camera as apposed to a custom DCP which is fixed. My Fuji camera has “film simulations” each with their own tone curve. This tool can look at the embedded jpg image and match what the camera was set to at the time of the image.

Does the selected Film Simulation effect the embedded JPG of the raw file?

As far as I know it does. Maybe someone more knowledgeable than I could correct me though

Yes, it does.