mmColorTarget v2.0

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Contributor: Marco Meyer
Matches colors of two input images using the MacBeth ColorChecker and outputs a ColorMatrix. Requires the additional Python module 'numpy'.
9.0, 8.0, 7.0 or later
21 May 2016

Useful Nukepedia Tool #8. Explore this video:   Tool Video


- Make sure you have Numpy installed, compatible and accessible with your Nuke version. (see Blogpost with additional Information )

- Plug two images showing a MacBeth Colorchecker into the source and target inputs.

- Corner Pin the source and target sampler to its corresponding ColorChecker and adjust the sampler Size

- (Switch inputs using the 'currentView' dropdown)

- Hit the 'Calculate Matrix' Button to get the output ColorMatrix.

Demo Video


Changes v2.0:
- More intutive UI with callbacks
- Fixed a problem introduced in Nuke 9.0v8 that broke the entire functionality
- The reference target now comes with a dynamic colorspace selection instead of fixed sRGB Values. (generously provided by Thomas Mansencal at
- Additional sampling method 'no clip' (EXPERIMENTAL!)
- More stability due to no more expression-based-sampling in the background 


Tested successfully on Windows 7/10 (Nuke7/8/9) and CentOS 6/7 (Nuke7/8/9/10b)

Mac Users: The Gizmo should also work on Mac, but you need to find/compile a compatible version of numpy yourself, since i don't have a Mac. Please help me out be sharing your information on this.



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# Jason Huang 2014-05-06 10:11
Thanks so much!!! I am screaming if it is what I think it is that can save me from buying HDR Shop 3.0 for $200 and just for this particular feature.... :D
# Manuel Flemming 2014-05-06 17:29
Thanks a lot! That's very useful!!
# Daniel Brylka 2014-06-21 10:42
Failed to try this on Nuke8 OSX, I found NumPy (not the latest version as a .DMG), installed it, Python 2.77 itself on the system can import "NumPy", but inside of Nuke I get just an error that it is not finding it. Can someone tell me what else I need to do?

# Marco Meyer 2014-07-01 10:03
the easiest way to test would be to copy the numpy folder that's located in your python site-packages (on OSX it should be something like "/Library/Pytho n/2.7/site-pack ages") to your "/Users/YOURNAM E/.nuke" folder and try "import numpy" again.

the other way would be to add the following to your file:
import sys
sys.path.append("/Library/Pytho n/2.7/site-pack ages")

It's still possible that you'll get an error if the compiler version doesn't match, which is the point where i can't help any further, since I didn't get enough feedback from Mac users yet. But it should at least find the module now and tell you what's going on.

I hope it helps, and please share your information if you suceeed.
# guillem ramisa 2014-09-20 16:31
Hi Marco,

I've found the NumPy installer (1.6.1) for Python 2.7 for Mac. I'm running a mac osx 10.6.3 with NukeX 8.0.3.

It works fine with osx 10.6

I've checked in the OSx command line if the package got installed and yes, it worked and found all the files

I found the folders inside "/Library/Pytho n/2.7/site-pack ages" and copied to: .nuke/Framework s/Python.framew ork/Versions/2, 7/lib/python2.7 /site-packages" I'v copied there the numpy folder.

When I load the gizmo, it works well but when I try to calculate the matrix there it appears an error: " .../site-packag es/numpy/core/m no matching architecture in universal wrapper "

I've tried importing with the command but it does not work.
import sys
sys.path.append("/Library/Pytho n/2.7/site-pack ages")

Is there any way I can fix it??or I'm doing something wrong..?
I would appreciate any help.

Thanks Marco and amazing gizmo!

- Guillem R.
# Marco Meyer 2014-09-23 20:27
Looks like there's a 32bit/64bit-pro blem. Your numpy has to be 64bit to run with nuke, i guess.
You might wanna check any of those solutions:

Have you already tried any of the official installers for osx10.6? For example:

Providing google help is really the best i can do right now :(
# guillem ramisa 2014-09-25 16:27
Yeah! It worked perfectly!

Very thanks Marco! I've been searching for this for a long time!
I'm the first Mac user to get this working??

I've just added the new site-packages created on the /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages

Never underestimate google help :-)

Thanks again!!
# Marco Meyer 2014-09-26 16:55
Awesome, glad to hear that :)
Well you're not necessarily the first Mac user ever to get it working, but you sure are the first to give me some positive feedback.
So thanks a lot for sharing!
# Dani Kei 2014-10-08 12:07
Hey, would you mind uploading the "site packages" that works on mac? I'd love to get numpy working and mmcolortarget !!! Or writing a small explanation on how you got it to work!
# Iván Martínez 2015-05-18 17:03
Awesome Marco Meyer.
Could you give us a tip for work with spydercheckr 24 without hide 2 rows ( it are inverted in this color card) :sad: (second color and grey)
Thank you!!
# Thomas Mansencal 2016-01-14 04:31
Well, you could still manually crop and flip the offending rows to match XRite / GretagMacbeth colour rendition charts, however I would not do that because there is no guarantee that the samples between the two brands have the same colours. This need to be checked before doing any colour fitting.
# Dennis Serras 2015-07-10 23:24
Thanks for the tool, it is a good design and well made. I tested it by taking a color chart, messing up the colors, then bringing it back into Nuke. I found two issues worth addressing:

1. It does not manage levels well - I would look at adding an exposure, levels, or some other way of balancing brightness before applying the chart. I fixed that by manually adjusting levels first.

2. It crashes in Nuke 9.0.3. Numpy works in 9 OK - I was able to test it - so something else isn't working.

Thanks again!
# Tigran Stepanyan 2016-04-19 16:48
How can i fix this problem?
/usr/local/Nuke9.0v8/ version `GCC_4.2.0' not found (required by /lib64/
# Daniel Brylka 2016-05-22 10:11

I found this morning the new video. Thanks for making it. I followed along on OS X 10.11.5 with Nuke 10.0v1 Non-Commercial.
I still can't make it work.

The gizmo is coming with a .json file, is that also belonging in the gizmos folder?

When I hit "calculate" I get the following error:
'NoneType' object has no attribute 'knob'

Did I install it okay? Is there a way to check inside of Nuke?
And what does this error message means?

Thanks in advance,

Best regards

Daniel (toodee)
# Frank Rueter 2016-05-22 23:01
Sounds to me like the Non-Commercial restrictions in the python interpreter are causing this.
# Daniel Brylka 2016-05-23 08:48
Thanks Frank,

you are right, in the normal licensed version it works fine.
It would be nice that the Foundry would actually give the user some hints, that a restriction causing an error in the NON-COM. version.
# Jason Freets 2016-09-03 07:56
I'm using Nuke10 Non-Commercial and can't get this to work in either Linux or Windows:

Current problem is:

'NoneType' object has no attribute 'knob'.
# Brendan Coyle 2016-12-18 05:03
awesome gizmo! only wish was that it would work when matching an upside down chart. seems to get funky. otherwise i just flip the image and match the chart and it works! thanks
# kasiflaco guyi 2017-03-14 16:45
Thanks so much from Venezuela
# Pedro Andrade 2017-06-06 13:01
Hey Marco! This seems pretty nice. Can you please share the documentation for the math behind the transform matrix? Thanks
# Thomas Mansencal 2017-06-06 19:52
Quoting Pedro Andrade:
Can you please share the documentation for the math behind the transform matrix? Thanks

It is a Multivariate Linear Regression: and uses tsq:
# Pedro Andrade 2017-06-07 10:03
Thanks a lot Thomas.

One thing that seems to have always some discrepancy when comparing different documentations are the RGB values on the Macbeth chart. For example, here on Nukepdia the values used on mmColorTarget tool are different to the ones of V_ColorRenditio nChart... Also different documents seems to have different information on the normalized values of RGB for the same illuminant:

Can anyone expand on this differences and how / where these values of this tool were obtained?
# Thomas Mansencal 2017-06-07 10:13
Quoting Pedro Andrade:
Thanks a lot Thomas.
Can anyone expand on this differences and how / where this values of this tool were obtained?

Absolutely :) As explained in the description they were generated by myself, the file that yielded the value is there:

They are based on XRite ColorChecker 2005 values as described here:

Now colour rendition charts are never produced equal, so it is normal to find discrepancies between them, not only that but there are also differences in the various RGB colourspaces / whitepoints values depending where you source your data.

This reminds me that I should regenerate the Notebook/JSON file with the latest values content from Colour.

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