[Kdenlive-devel] Color correction tools: How and where to implement them?

[Simon Eugster]

2010/7/15 Dan Dennedy <dan at dennedy.org>:
> On Thu, Jul 15, 2010 at 1:49 AM, Till Theato <root at ttill.de> wrote:
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>> On 07/15/2010 09:52 AM, Simon Eugster wrote:
>>> 2010/7/14 Till Theato <root at ttill.de>:
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>>>> On 07/14/2010 07:13 PM, Dan Dennedy wrote:
>>>>> On Wed, Jul 14, 2010 at 9:00 AM, Simon Eugster <simon.eu at gmail.com> wrote:
>>>>>>>> * 3-Way color correction works basically quite well,
>>>>>>>>   but the usability is terrible.
>>>>>>>>   If you want to change the blacks, you have to rise the black
>>>>>>>>   value to see colors in the color picker, and at the end make
>>>>>>>>   it nearly black again. Would be much better to just chose a
>>>>>>>>   color and not having to worry about black.
>>>>>>>>   Also is it not very convenient not to have a live preview.
>>>>>>>
>>>>>>> All Kdenlive effects have live preview. So, a simple enhancement to
>>>>>>> toggle that would help.
>>>>>>
>>>>>> Well, there is live preview as soon as the color has changed in the
>>>>>> widget. But this is only the case when the color picker has been
>>>>>> closed already. There should be a built-in color picker.
>>>>>
>>>>> Yeah, like I suggested for white balance.
>>>>>
>>>>
>>>> I will take a look at this one. Maybe we could also reuse a color
>>>> selector from krita.
>>>
>>> Perhaps something like the HSV color wheel here
>>> http://en.wikipedia.org/wiki/Color_wheel would be good because even
>>> for high black values you still see the color.
>>>
>>> Perhaps a wheel that just ignores the black value (like a YUV wheel
>>> with fixed Y) would suit even better. Especially as the vectorscope
>>> uses YUV as well, this would make color corrections much easier. I'm
>>> currently trying (or, intending to try, should be learning actually)
>>> to produce a YUV circle for the vectorscope as background, but this
>>> could also be used for a color wheel later. When I get it, this
>>> shouldn't even be too difficult.
>>> Perhaps we'd still need to add the Y component separately.
>>>
>> What I thought of was Krita's Triangle Color Selector
>> (http://lukast.mediablog.sk/i/colorchoosers/krita-color-choosers.png).
>> However it is RGB based.
>
> I just realized that for White Balance, I was thinking about the
> eye-dropper. It would be nice to choose a color via eyedropper for
> White Balance and/or color-palette for other effects without the
> issues of a modal dialog.

I think that is exactly what I tried to express :)

Please take a look at r4582. I've added a method
Vectorscope::yuvColorWheel which creates a YUV color wheel.
It is totally amazing what graphical effects you get when ignoring
char overflows.
I mean. The modified color wheel might suit quite well as color
picker. Perhaps it would require some more modifications to get more
differentiable saturation. (Actually the modified one was the original
YUV wheel which I identified as being just wrong. But it does seem
useful.)

You can see the wheel in the vectorscope, when changing the background
(via combo box there). Works in an empty project as well.

@Dan, I will answer your previous mail later, need to think about some
things first.


Making the vectorscope was really interesting :) I learned quite a
lot. And imho it's already quite cool now. Still some things to
improve though.


Simon