Auto Levels: calculate based on cropping

[Beep6581]

Originally reported on Google Code with ID 720

Currently auto levels are calculated based on the full image area.
Improvement suggestion: calculate based on image content within the crop.

Ideally, there should be a checkbox next to Auto levels button- "crop-based".
When crop is changed and auto levels are selected and "crop-based" checkbox is selected
auto levels should be recalculated.

This feature would allow to perform exposure setting based on selected region of interest.
User may temporarily set cropping to the region of interest, execute auto levels "measurement",
deselect auto levels button (EC and black stay unchanged (this is current functionality)),
set final crop.

Reported by michaelezra000 on 2011-06-06 01:59:37

[Beep6581]

I don't really see the point.  Auto levels is the lazy person's conversion method. 
If one is going to pay attention to the image enough to select a crop, how much work
is it to move the exposure slider to taste in addition?

Reported by ejm.60657 on 2011-06-06 02:45:41

[Beep6581]

True, this is the lazy side of me speaking - when I convert the family pictures:)

Reported by michaelezra000 on 2011-06-06 02:53:47

[Beep6581]

My problem is that many of my family pictures happen to have reflective surface of chairs
- my parent's fault in decorating, really:). Due to flash the specular highlights are
near blown in furniture reflection and this messes up the autolevels. 

Reported by michaelezra000 on 2011-06-06 02:58:57

[Beep6581]

Giving it a second thought.. I think auto levels should be always crop based (why should
auto levels be based on image data outside the crop anyway?).

This would serve all purposes and no extra check box is needed.

Reported by michaelezra000 on 2011-06-06 03:24:52

[Beep6581]

This is a very old feature request from the forums. I agree with Michael, I want RT
to only take the cropped part of the image into account when setting auto levels and
when calculating the histogram, for obvious reasons.

Emil I disagree with your remark that auto levels implies that the photographer is
being lazy and not paying attention. Auto levels is supposed to offer a good starting
point, why should we settle for a bad starting point? All it takes is one bright light
or reflection in a cropped-off area to throw auto levels off track. The cropped-off
area is by definition something we cut off, something we do not want to have in our
photo, therefore it is silly that RT should adjust the large part of the photo which
we do want to keep based on a small troublesome part which we do not.

Reported by entertheyoni on 2011-06-06 03:40:10

• Labels added: Type-Enhancement
• Labels removed: Type-Defect

[Beep6581]

Still not done in 4.0.11.105

I agree, it's a good feature. I thought it was already working in the cropped area
but just tested and it's true changing crop does not make any changes to auto levels,
even if the button is pressed again.

Reported by torger@ludd.ltu.se on 2013-11-05 11:51:12

• Labels removed: 3.1B1

[Beep6581]

Issue 2236 has been merged into this issue.

Reported by entertheyoni on 2014-02-16 18:22:23

[Beep6581]

Reported by entertheyoni on 2014-02-16 18:22:57

• Labels added: Component-Tool
• Labels removed: Priority-Low, Component-UI

[Beep6581]

Still not in 4.1.
Since the histogram is based on the crop, maybe making Auto Levels the same is just
a matter of plugging it into a different socket? :]

Reported by entertheyoni on 2014-08-27 12:30:18

[leodp]

Hi, I would like to add an user case: Old slides digitized with a DSLR 1) The edge of the acquired image is directly illuminated by the slides light (maybe passing through the film holes)=>This defines the white level 2) The edge of the film is darker than the black level of the slides image=>This defines the black level 1 & 2 above cause wrong auto exposure correction and also wrong white balance correction. The issue can be overcome if it would be possible to define a crop area (center of the image) for the auto exposition and AWB (similarly to what already done by spot WB, but more generic). The .pp3 profile with the specific crop area can then be batch-applied to all the scanned images. Baseline issue: scanning hundreds of slides is quite time consuming. RAW computerized processing (read:rawtherapee) should not take more time than the scanning itself, but profit from the automatic nature of information processing. Searching with google "digitizing slides" returns 337000 results. This open issue may be of interest to more than only a few "lazy persons". https://encrypted.google.com/search?q=digitizing+slides&hl=en&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjPpZ783L7WAhUKvBoKHWSdCt0Q_AUIDCgD&biw=1032&bih=543

Leo

[heckflosse]

@leodp There are thoughts to allow a raw crop in rt. That would mean a crop of the raw file directly after decoding phase. That would solve your issue. But currently these are just thoughts...

[leodp]

That would help. But will sacrifice the film and the image edges, which are part of the flair these images have. I like particularly the not straight edge between the image and the black frame of the film. But this is just my thought.

[heckflosse]

@leodp I see your point, but that's a different issue then. This one is about Auto Levels: calculate based on cropping

[nahuelaguilar93]

I agree that this would be a great feature. Given the possition of my white balance card in the image, this will allow me to automatically crop and auto white balance the image by just properly generating a pp3. Hope it's available soon.

[deusexmamiya]

Another vote for this. It's REALLY needed for timelapses under changing light conditions.

Here's an example. Two consecutive frames from a Milky Way timelapse. When the second camera's LCD screen changed in the bottom corner to a fainter, less blue light, the AutoWB changed for the whole image, and made the yellowish Milky Way less visible. If I could user-define an "Auto WB box", covering in this example the upper 80% of all the images, it would avoid this area where the light changes.

Now if you're wondering "Why doesn't he set a custom WB and use it for all the timelapse frames?" - that's even worse. The sky was entering twilight (becoming gradually much bluer), so the Milky Way stands out much better when Auto WB cancels out this progressive blue-ing. A fixed WB just fails completely. Auto WB is best, but it really needs the addition of that extra control over what block of the image is included in determining Auto WB. (Note - this is separate to the cropping box. I don't want to crop the images at all in this case).

[nomar500]

I thought I had already voted for this feature. 👍