Photoshop curves for Final Cut at DVinfo.net

Dominik Seibold · October 5th, 2010, 02:27 PM

I'm about to write a plugin for Final Cut which should imitate the Photoshop RGB-Curves. But I have one problem/question which I just can't get answered even with extreme googleing:
What is the interpolation-formula Photoshops curves uses to interpolate between the points?
It seems to me that Photoshops curves inpolation is both unique out of all curves out there (Apple Color, etc.) and best regarding the photographic quality compared to the effort to tweak a curve. Other implementations of such curves-tools often use interpolation-schemes like Bezier, but they feel really inadequate for this application. So I absolutely want to implement the interpolation like Photoshops curves does, but I have absolutely no idea what the formula could look like.

William Hohauser · October 5th, 2010, 04:49 PM

Be careful, it might be patented.

Dominik Seibold · October 5th, 2010, 10:06 PM

The plugin is now almost done. You can download and test it here:
http://www.dominik.ws/rgbcurves.zip
I also attached a screenshot of it to this post.
The only missing thing is a good interpolation between the points. Currently linear interpolation is used. If someone of you could give me a hint what kind if interpolation I should implement, I will do it! :) Please give me some feedback what you think about the plugin!

Chuck Spaulding · October 6th, 2010, 12:22 AM

That's a great idea. I always thought they were just B-splines. I think it would be a lot more useful if you could edit the curves directly, break them at the point so they can linear in and Bezier out.

I thought Apple started improving their graph editor, it was good for a while in variable speed, but it never really went anywhere.

Is there a high-pass filter in FCP? That's a good filter for sharpening, if your taking requests...

Dean Sensui · October 7th, 2010, 03:32 AM

A suggestion: Use Color.

It already has curves and is an immensely powerful color correction tool.

Dominik Seibold · October 7th, 2010, 05:40 AM

Quote:

Originally Posted by Chuck Spaulding

I always thought they were just B-splines.

Thank you! I finally discovered that Photoshops curves uses so called "natural cubic splines". I implemented them now into my plugin. Here you can download and install the result (I used fxplug sdk 1.2.5):
http://www.dominik.ws/rgbcurves.zip
Btw., a 16bit (unsigned short) per channel lookup-table is internally generated and used, so the image processing is fast and posterizing free (but not GPU accelerated right now. If you know how to write an ARB fragment shader which uses a lookup table, please let me know!).
A sreenshot is attached to this post which shows the plugin in action.
Please give me some feedback!

Quote:

Originally Posted by Chuck Spaulding

Is there a high-pass filter in FCP? That's a good filter for sharpening, if your taking requests...

What kind of high-pass filter? Like the simple sharpening filter or more like unsharp mask?

Quote:

Originally Posted by Dean Sensui

A suggestion: Use Color.

I don't like the behaviour of Colors Curves. Also I don't like to even start Color up. I think the workflow is very inconvenient.

William Hohauser · October 7th, 2010, 01:09 PM

Your filter sounds good but the download installer file seems to be empty, only 16k. Could you post the filter without the installer package?

Simon Denny · October 7th, 2010, 01:25 PM

Thanks Dominik,

Plugin works great and I like it. Is there anyway to add a point to the curve rather than adding a point as it moves. I say this because as I add a point the cure moves and I may not want to add a point in that spot.

Cheers

Dominik Seibold · October 7th, 2010, 01:29 PM

Quote:

Originally Posted by William Hohauser

Your filter sounds good but the download installer file seems to be empty, only 16k. Could you post the filter without the installer package?

Well, the installer isn't empty, but of course (I guess it's a trust issue) I can also give you the raw fxplug File/Folder:
http://www.dominik.ws/rgbcurves2.zip

Dominik Seibold · October 7th, 2010, 01:45 PM

Quote:

Originally Posted by Simon Ash

Is there anyway to add a point to the curve rather than adding a point as it moves.

I just added this feature. With the right mouse button you can now add a point which initially doesn't alter the curve (x value comes from your mouse, y value from the current curve). I already updated the files rgbcurves.zip and rgbcurves2.zip on my server, so you can immediatelly download the new version.

William Hohauser · October 7th, 2010, 08:26 PM

Quote:

Originally Posted by Dominik Seibold

Well, the installer isn't empty, but of course (I guess it's a trust issue) I can also give you the raw fxplug File/Folder:
http://www.dominik.ws/rgbcurves2.zip

It's not that, but it didn't install after running it. But thanks for the direct plug-in. I'm going to try it now.

William Hohauser · October 7th, 2010, 08:53 PM

Not to be a nuisance but the plug-in unzipped as a folder.

Dominik Seibold · October 7th, 2010, 10:26 PM

Quote:

Originally Posted by William Hohauser

Not to be a nuisance but the plug-in unzipped as a folder.

Yes, you have to copy that folder to /Library/Plug-Ins/FxPlug (or ~/Library/Plug-Ins/FxPlug). But I guess the folder is already there, because you already executed the installer package. I'm not sure why my plugin isn't shown in your plugin-list. Which version of Final Cut do you have?

Simon Denny · October 8th, 2010, 02:30 AM

Hi Dominik,

Where can I find the updated cures version for downloading?

Cheers

Anthony J. Howe · October 8th, 2010, 05:28 AM

I have been testing this Dominik, and it works great, what a great time-saver and so easy to use.
Well done and thanks.

October 5th, 2010, 02:27 PM	#1
Dominik Seibold Major Player Join Date: May 2008 Location: Nuremberg, Germany Posts: 285	Photoshop curves for Final Cut I'm about to write a plugin for Final Cut which should imitate the Photoshop RGB-Curves. But I have one problem/question which I just can't get answered even with extreme googleing: What is the interpolation-formula Photoshops curves uses to interpolate between the points? It seems to me that Photoshops curves inpolation is both unique out of all curves out there (Apple Color, etc.) and best regarding the photographic quality compared to the effort to tweak a curve. Other implementations of such curves-tools often use interpolation-schemes like Bezier, but they feel really inadequate for this application. So I absolutely want to implement the interpolation like Photoshops curves does, but I have absolutely no idea what the formula could look like.

October 5th, 2010, 04:49 PM	#2
William Hohauser Inner Circle Join Date: Dec 2005 Location: New York City Posts: 2,650	Be careful, it might be patented. __________________ William Hohauser - New York City Producer/Edit/Camera/Animation

October 5th, 2010, 10:06 PM	#3
Dominik Seibold Major Player Join Date: May 2008 Location: Nuremberg, Germany Posts: 285	The plugin is now almost done. You can download and test it here: http://www.dominik.ws/rgbcurves.zip I also attached a screenshot of it to this post. The only missing thing is a good interpolation between the points. Currently linear interpolation is used. If someone of you could give me a hint what kind if interpolation I should implement, I will do it! :) Please give me some feedback what you think about the plugin! Attached Thumbnails

October 7th, 2010, 03:32 AM	#5
Dean Sensui Inner Circle Join Date: Oct 2001 Location: Honolulu, HI Posts: 2,054	A suggestion: Use Color. It already has curves and is an immensely powerful color correction tool. __________________ Dean Sensui Exec Producer, Hawaii Goes Fishing

October 7th, 2010, 01:09 PM	#7
William Hohauser Inner Circle Join Date: Dec 2005 Location: New York City Posts: 2,650	Your filter sounds good but the download installer file seems to be empty, only 16k. Could you post the filter without the installer package? __________________ William Hohauser - New York City Producer/Edit/Camera/Animation

October 6th, 2010, 12:22 AM	#4
Chuck Spaulding Trustee Join Date: Nov 2004 Location: Thousand Oaks Posts: 1,104	That's a great idea. I always thought they were just B-splines. I think it would be a lot more useful if you could edit the curves directly, break them at the point so they can linear in and Bezier out. I thought Apple started improving their graph editor, it was good for a while in variable speed, but it never really went anywhere. Is there a high-pass filter in FCP? That's a good filter for sharpening, if your taking requests...

October 7th, 2010, 01:25 PM	#8
Simon Denny Trustee Join Date: Jul 2007 Location: Australia Posts: 1,409	Thanks Dominik, Plugin works great and I like it. Is there anyway to add a point to the curve rather than adding a point as it moves. I say this because as I add a point the cure moves and I may not want to add a point in that spot. Cheers

October 7th, 2010, 08:53 PM	#12
William Hohauser Inner Circle Join Date: Dec 2005 Location: New York City Posts: 2,650	Not to be a nuisance but the plug-in unzipped as a folder. __________________ William Hohauser - New York City Producer/Edit/Camera/Animation

October 8th, 2010, 02:30 AM	#14
Simon Denny Trustee Join Date: Jul 2007 Location: Australia Posts: 1,409	Hi Dominik, Where can I find the updated cures version for downloading? Cheers

October 8th, 2010, 05:28 AM	#15
Anthony J. Howe Regular Crew Join Date: Jun 2008 Location: United Kingdom Posts: 55	I have been testing this Dominik, and it works great, what a great time-saver and so easy to use. Well done and thanks.