How to remove the cloudiness in rawtherapee

Software RawTherapee
21

It has a positive connotation in this meaning, not trick like deceiving.

I have to say that if there is any good hidden in a photo you find it, it is a wonderful talent.
Thank you for all your help again.

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22

Let me explain why I donā€™t think itā€™s a trick:

  1. assume you you have a (very) low contrast photo
  2. why itā€™s low contrast?
  3. if itā€™s low contrast because of haze or internal camera/lens reflections, there maybe regions which should be black, but are not black because the haze or internal reflections add light to the regions which should be black.
  4. So, just measure the minimal rgb values of the raw file and subtract them for this kind of images

The only thing poor_man_dehaze branch does, is to spit out this values in console.

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23

Sorry, ā€œtrickā€ was perhaps not the right word to mean that it is so simple and effective with no fancy math or zillions of sliders.
When do you intend to introduce this as an automatic function in the dev branch?

24

Would it be possible for someone to point me to a read on black point compensation in RawPedia?

Thanks

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25

What is wrong with using the search field, or literally look up the link on the main page?

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image1699Ɨ1059 252 KB

27

Apologies for being slow but how I change the licence on this.

Thanks again for all the help.

28

Roel, I was searching for ā€œblack point compensationā€ as it was referred to in the discussion. Thatā€™s why I didnā€™t find anything.

29

I can implement it for 5.9. The question is, where to place it in UI. Technically it should be in the raw blackpoints tool. Conceptionally it could be also in the Haze removal tool. I prefer the first.

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30

i also would prefer it in RAW blackpoints tool. Would it be possible to put an internal link from haze removal tool to there? So the user could choose individually, which way he would prefer ā€¦

31

I think a checkbox for ā€˜Black point dehazeā€™ could be added to the Haze removal panel, while in the background the GUI for the Raw black points would be updated.

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32

Sometimes messing with raw black points can cause undesired color impactsā€¦

Iā€™ve found (when working with earlier versions of the film negative inversion tool, I havenā€™t retried with more recent versions) that messing with the LAB curve tool (basically have a linear ā€œcurveā€ that started at a nonzero value) worked well.

To provide a screenshot Iā€™ll need to be home (I am not now).

33

Sure, but also vice versa. Haze can cause undesired color impacts, which then can be corrected by changing raw black pointsā€¦

34

Yes but if the checkbox is in Haze removal tool, users will not be tempted to mess with that for other use.
So I Agree with @Thanatomanic

35

I think that the automatic checkbox must be in the Raw Black Points module to have it separated from the Haze Removal module, because that way I can have the automatic checkbox activated and at the same time have the Haze Removal module deactivated.

36

You can put strength to 0

37

Good point. Furthermore I think, changing something in one tool (a new auto checkbox in dehaze), which changes values in a different tool (raw black levels, which is also in a different tab), is very confusing.

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38

I agree. I think a checkbox in the raw tab would be the most logical thing to do. Maybe have a short information about this function in the mouseover text of the dehaze slider?

3 Likes
39

Makes sense for meā€¦

40

It would be a solution. I understand that it is more practical, but it tries to avoid confusion.

41

In my opinion playing with the Raw Black Points is good for the image, and even if it has a side effect of removing haze to some degree, it shouldnā€™t be focused on that. Black Points are a different matter than dehazing.

Improving blacks on any image is usually good, but having a button that automatically removes all the haze in an image is not so good. One of the benefits of the Dehaze tool is that you have control on how much haze you are going to remove. Thatā€™s currently not the case with the auto-Black Points: how can I easily improve the black points of the image without removing all the haze? Yes, weā€™ve had those Black Point sliders all the time at our disposal. But I mean Ā«an easy wayĀ».

Perhaps one solution would be adding an auto-calculation check box in the Black Points tool, and adding a Strength slider. That way we could find a nice compromise between having both good blacks and certain level of haze.

Having haze in images is not always a bad thingā€¦

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