Using displaycalGUI to profile a projectory array

[kevi...@insightdigital.org]

I'm beginning to use displaygalGUI to profile an array of nine laser/LED hybrid projectors, as each has an individual color cast that jumps out at viewers when viewing images across projectors. Our projector array is hung from a ring, and focused on a (continuous) cylindrical screen.

Here's what I plan to do. Please chime in if you have any suggestions!

- Use our i1 Display Pro colorimeter and displaycalGUI software to create ICM profiles for each projector

- Export a 3D LUT for each projector with tools:Create 3D LUT. When generating 3D LUTs I've been using 'rec709.icm' as the 'source profile' and the individual ICM files for each projector from Argyll as the 'target profile'.

- Shoot SLR reference on flat screen for each projector to characterize gamma vignetting

- Slice test images into 9 1920x1080 images for each projector in the array, applying the individual projector LUTs:

sam do r input.#####.jpg // lut rec709_to_projector_n.spi3d // w output.#####.jpg

- Check color matching by projecting images

- Test two-projector blends

We have been mastering our images in REC709 space, the 'native' color space for HDMI (from NukeX). A couple specific questions:

- Since our projection environment is 360^, bounce light from other projectors is a significant source of ambient light. While I trust that I should calibration each projector one at a time, how should I account for the ambient light contributed by each projetor's neighbors?

- One last question, perhaps a very obvious one: how can I set JPEG compression values for output JPEG images, as per the syntax above?

Thanks in advance for any good thoughts on this workflow from the community!

[Clément Champetier]

Hello Kevin,

Your project sounds very exiting!

But I am not an expert in these kind of installations, so I can't help you about the ambient lights of projectors.

However, I can give you some information for your last question.

You can set JPEG compression by using the "quality" parameter of some writers (jpegwriter, turbojpegwriter and oiiowriter), with value between 0 - 100.

If you know that you generate jpg images, your command line should be:

sam do r input.#####.jpg // lut rec709_to_projector_n.spi3d // turbojpegwriter output.#####.jpg quality=100

Regards,

Clement

[kevi...@insightdigital.org]

Thanks for the help with JPEG encoding quality!

In my note above, I may not understand source and target profiles referred to in Tuttle's tools:Create 3D LUT.

Here's my edited approach to profiling the projectors in a group -- will this work?

- Use our i1 Display Pro colorimeter and displaycalGUI software to create ICM profiles for each projector

- Export a 3D LUT for each projector with tools:Create 3D LUT.  

- When generating 3D LUTs, use 'rec709.icm' as the 'source profile' and the individual ICM files for each projector from Argyll as the 'target profile'.

- Apply the individual projector LUTs:

sam do r input.#####.jpg // lut rec709_to_projector_n.spi3d // turbojpegwriter output.#####.jpg quality=100

- Check color matching by projecting images

Thanks again,

-Kevin