Custom processing for JPEG (Tone curve, CA ...)

[toinech]

> unsigned short curve[4][1024];
> ...
> pixVal[k]=curve[2*(i&2)+(k&2)][pixVal[k]]; // Assumme Bayer

The expression 2*(i&2)+(k&2) can has 0, 2, 4, 6 as the result, but declaration is "curve[4]".
Is it supposed to be 2*(i&1)+(k&1)?

Thanks for catching this bug.
By the way will there be any performance gain to have this section replaced by inline assembly?
The code is supposed to slice an 80 bit bloc into 8 blocs of 10 bits to use them as index to replace those 8 blocs of 10 bits and reassembling the whole thing.

I am pretty lame with inline assemble and would need help there.

[wontolla]

Well I finished the coding and run a couple of test...

Hi toinech, it looks very interesting. My questions are threefold:

What does your code do?

How do we add it to CHDK?

Can you post some results for us to see?

Thank you.

[toinech]

What does your code do?

Emulate the curve feature of P*shop. Or some crude imitation of it.
The code load a binary file that contains 4 response curves for the following pixel pattern in the raw file:

  (0)(1)
  (2)(3)

The response curve will be applied to the RAW data before it gets converted to JPEG and after it is saved.
See the follow more graphical explanation from Mediachance: Tone Curves

Each of the curve is supposed to correct a color. I provided some more cryptic explanation earlier in this post.

How do we add it to CHDK?

It is still work in progress: I am still working on an offline tool that would generate the curve files.
I am still need to verify the exact pattern of the different 'color pixels' (see comments below)

Though I have the feeling that all of this may get to a dead feature and do not want to clog the
source tree with this as yet.

Can you post some results for us to see?

For now I only try 6 different curves:
- 1 to 1 level transformation (i.e no change) for the 4 curves => OK
- 1 to 1/2 level for the 4 curves => OK
- 4 curves with a 1 to 1 level transformation and zero for the other 3 => odd result to be understood.
  I was expecting to verify that by applying the different filter against a white picture and get the different colors
  corresponding to each of the colored pixel on the CCD sensor.
  I did not get the expected result: May be the assumption on the color pattern is not correct.

The speed is also too sluggish.

I also found out in the mean time that the polarizer can't be simulated and that the camera performance is too
slow for CA correction algorithm.

[Barney Fife]

Deleted

[toinech]

This might be an excellent way to "fix" the color shift that happens when averaging RAW images for in-camera HDR. Averaging 3 or 5 bracketed RAW frames seemed to provide some excellent results in another thread where people were testing this. But highlights were getting strongly shifted into magentas/reds (most likely due to not having a proper color profile for RAW import that wasn't expecting that many frames added together needing compensation more accurately).

With the A610, it seems possible to go to "my colors" mode and adjust the parameters in "Custom color" mode and develop the picture with those.

I hope you don't give up working on this. For the advanced photographer this would be an excellent addition. The more that can be done with some simple and well-tested defaults in our cameras, the less that needs to be done in editing. I for one would love to be able to tone-down the contrast a bit more in my camera (for a simple example). Canon loses too much dynamic range in its JPGs by trying to produce garish "advertising" images to the average consumer.

With the A610, it seems to be possible to tone down the contrast. The "photo effects" mode offers some of the functions.
May be it is worth while to create means to save specific sets of values for the "photo effects" and "custom color" parameters  in loadable configuration files.

[Barney Fife]

Deleted

[toinech]

After further review of the DCRAW source code it looks like the interpretation is correct.
We should have the following matrix

  (G)(B)
  (R)(G)

For the off line editor - my skills are to limited to produce anything helpful.

Can anybody out there skilled with interactive development experience help contribute a decent curve editor?

[toinech]

Finally I got to finish the curve editor and associated tools... and some test successfully (1 Stop , Gamma correction)

The adjustment of curves can be some home counter intuitive and tricky for color adjustment.
I joined the Windows NT tools for your trial.

Are attached below the tools and the code snippets to be inserted in the trunk.
(I do not have access to update the sources on SVN)

Have fun.

Attachment removed ... to make room for more recent tools

[wontolla]

Excelent toinech!

Maybe you want to compile for all cameras so all the people can try it before commiting to trunk. In case there are bugs/suggestions etc.

//for all cameras
gmake batch-zip

Have fun!

[DataGhost]

By the way will there be any performance gain to have this section replaced by inline assembly?
The code is supposed to slice an 80 bit bloc into 8 blocs of 10 bits to use them as index to replace those 8 blocs of 10 bits and reassembling the whole thing.

I am pretty lame with inline assemble and would need help there.

Maybe, I might have time.... thursday or friday, I can have a look at what your code compiles to and see if it can be done quicker. I have the feeling that gcc will try to do this with about 4 registers (it's hard to calculate register needs and allocate them) so I suspect it's going to have to load a lot from memory (not considering the complete RAW data). Also, your loops are 'wrong', the camera will probably have to recalculate the loop invariant each iteration. If you reverse the loop (start high, do -- until == 0), you're coding 'for the architecture', gcc isn't smart enough to detect this. This might already speed it up a little.
(I've seen an extreme case which required 3 ops for the loop invariant (mov big value, add some, add some more), one for the iterator (add one) and one for the comparison itself (cmp), which was replaced by the one op 'subs iterator, 1' after reversing the loop)

[toinech]

Excelent toinech!

Maybe you want to compile for all cameras so all the people can try it before commiting to trunk. In case there are bugs/suggestions etc.

//for all cameras
gmake batch-zip

Have fun!

Here are some of them (butchered) by me ... as you will see
I have tested with A610 1.00f
Please let me know if your camera is not there - I don't want to overload the post...

I have also updated post#22 with a ApplyCurves tool that will work with multiple camera instead of the A610 only.

Update: If you are not too fond of the butchered version please use the Jucifer release (Thanks Jucifer): yet another personal CHDK build (against trunk revision 387)

Removed some binaries since Jucifer release.

[NewbieToobie]

Someone told me about this. I had to check. WOW!

I was hoping was to make posterization FX where 8 12 or 16 colors are used. Solarization where tone ranges are color inverted. Your curve editor doesn't allow for making straight lines. Stair-step and saw-tooth patterns. A single vertical line for monochromatic FX. Things like that.

Could you change the curve editor to have an option for straight lines point to point? Then all the above would be possible.

It also doesn't allow you to move the end points across the top or bottom to clip highs and lows, only the right and left sides to lower contrast. It could be used for histogram adjusts if end-point movement on the other axis was allowed. You could make a busy background all white to remove it. Great for silhouette portrait shots

This is like having a built in photo editor. Save folders full of your favorite special effects. I have to figure out how to do a fake infrared look. That would be neat!

I wonder how curves could be made to mimic glass filters. Is there a place online that publishes the curve patterns for glass filters? It wouldn't be too hard to match those shapes with the editor.

Could the curve editor be made part of CHDK? Load edit and save curves right in the camera?

[toinech]

Someone told me about this. I had to check. WOW!

I was hoping was to make posterization FX where 8 12 or 16 colors are used. Solarization where tone ranges are color inverted. Your curve editor doesn't allow for making straight lines. Stair-step and saw-tooth patterns. A single vertical line for monochromatic FX. Things like that.

Tool is not about color but about level of the primary channels.
You may not get the conversion you want.
I will be curious to see a solarization curve.

Could you change the curve editor to have an option for straight lines point to point? Then all the above would be possible.

Yes whenever I can get some time for it.
You are welcomed to modify the VB code if you want it quickly. Please let me know,

It also doesn't allow you to move the end points across the top or bottom to clip highs and lows, only the right and left sides to lower contrast. It could be used for histogram adjusts if end-point movement on the other axis was allowed. You could make a busy background all white to remove it. Great for silhouette portrait shots

By design the end points cannot be moved in X position or deleted. It took me sometimes to get that in the code.
You can add (A,0) and (B,1023) point to clip high and low levels.
You may not get the portrait effect you desire though.

I wonder how curves could be made to mimic glass filters. Is there a place online that publishes the curve patterns for glass filters? It wouldn't be too hard to match those shapes with the editor.

You can create your own. I am still working on a tool that could help build a curve profile between 2 shoots (one with filter and one without filter).
This was a secondary intention of the curve tool.

Nikon cameras have some loadable tone curves (.NTC files). Not sure if they are for color filters.

Curve may not be sufficient for color filters though. I am still learning about matrix color at this point.

Could the curve editor be made part of CHDK? Load edit and save curves right in the camera?

Yes
As a newbie I still have to figure it out though. May be in the tool section. Since I do not own the trunk I do not want to mess it up.
Only problem is that it is in VB.

[Steveo]

Hi

I might be being an idiot... or just a simple user trying to test this, but where or how do I get the curves into CHDK?  Obviously load them into the CURVES folder on the card and load them from the OSD... But what files am I loading onto the card?

Does anyone have any examples or test curves I can try out?  I am using an A570 with Jucifer's build.

Cheers

Steveo

[Jucifer]

create a .cv file with CurvesEditor (in CurveTools.zip)
(custom curves can also be used with raw develop)