THETA Z1 - Color Management Issues

[CorLeone]

This is a follow-up to the post in the following discussion related to color management when using the stitcher plugin for Lightroom:

How To: Edit and Stitch RAW DNG Images From RICOH THETA Z1 with Adobe Lightroom Classic CC and THETA Stitcher

A remark on my configuration shown above: Using Adobe RGB for the color space as input to the stitcher results in unnatural flat colors. Seems that the stitcher is not correctly doing color management. So use sRGB instead. This restriction should also be documented in the manual. Or even better, it should be fixed! Working in a Lightroom/Photoshop environment without supporting color management is a no-go! BTW: The THETA desktop app also handles colors poorly so don’t depend on it for color pro…

I did some further testing with the latest version of the stitcher provided by Craig, a beta version identifying itself as v1.00.4 (as the latest release version) but supposed to contain some improvements or fixes.

I started with a raw DNG file which has the following properties as reported by Adobe Bridge:

So, there is no color profile assigned, which is fine in this case, as this is raw data.

When importing this file into Lightroom, the raw data is interpreted (“developed”) and all further processing in Lightroom is done in the ProPhoto RGB color space. The May update of Adobe raw support contains support for the Z1:

Cameras supported by Camera Raw

When editing a file in an external application – such as Photoshop or the stitcher – a target color space has to be specified:

Lightroom then converts the colors from the internal color space ‘ProPhoto RGB’ to the target color space and adds a corresponding color profile to the output file.

When selecting ‘sRGB’ as the target color space, the file written by the stitcher has the following properties:

So, the stitcher’s output file still contains the correct color profile and is therefore handled correctly in Lightroom afterwards.

However, when selecting ‘Adobe RGB’ as the target color space, the file written by the stitcher has the following properties:

The color profile previously created by Lightroom has been removed – this is bad!

Files without a color profile are handled by Lightroom as sRGB, which is wrong in this case, resulting in incorrect (flat) colors.

Removing the color profile seems to be a bug in the stitcher, although I have no idea why this is done for Adobe RGB but not for sRGB.

This should be fixed as Adobe RGB is commonly used for high-quality image handling because it contains more colors than sRGB.

[CorLeone]

This is a follow-up to the posts in the following discussion related to color temperature (white balance) when processing raw DNGs in Lightroom:

Theta Z1 icc device profile

Hello– We are using the Z1 for HDRI capture and using dcraw to develop the dngs into linear tifs. I am noticing a bit of a color shift despite white balance and wonder if there is a device profile for the camera so we can get truly ‘neutral’ images from the DNGs that we can then feed to PTGui for stitch/merge. Thanks, micah

I did some further testing with the latest version 1.11.1 of the firmware and Adobe’s raw support (camera profile) for the Z1 introduced in May.

For this, I used a color chart illuminated by a studio light having a color temperature of 5500K.
(Note that the white background is paper with optical brighteners making it somewhat bluish. So consider the white patch of the chart only.)

My first shot was with CT setting ‘Auto’:

In Lightroom the CT/WB is reported as 4550K:

This value is quite off the expected value around 5500K!
Although the full image includes other subjects that probably have influenced automatic WB selection, this does explain the significant difference.

When doing a WB selection in Lightroom, the image gets a little more neutral (warmer):

In this case, the CT/WB is reported as 4850K – still quite off the expected value around 5500K:

My second shot was with a manual CT setting of ‘5500K’ with a result that tends to be on the warm side:

Surprisingly, in Lightroom the CT/WB is reported as 5400K – although it should exactly be 5500K ‘As Shot’:

When doing a WB selection in Lightroom, the image gets a little more neutral very similar to the first shot, although now cooling down:

In this case, the CT/WB is reported as 4850K, so at least this is consistent with the corrected first shot:

To sum up, what are the conclusions from this test?

1. The CT as set in the app is either not correctly recorded in the DNG or not correctly reported by Lightroom.
2. For neutral results, the CT has to be reduced by about 600K compared to the actual value of the illumination.

Can anyone either confirm or disprove these findings?

[CorLeone]

Here’s another color management issue, this time related to the THETA Desktop Application running on Windows 10.

This is a screenshot of a THETA image as shown in a standard image viewer:

And this is a screenshot of the same image as shown in the THETA Desktop Application:

Notice not only the overall differences in color and contrast, but also the strong posterization effect in the dark areas such as the water in the forground.

The THETA image is a JPEG file in sRGB color space with the correct ICC profile included and straight out of my old trusty THETA S, but the images from the Z1 show the same effect.

My monitor is calibrated using an ICC profile as my whole system setup supports color management.

Perhaps the THETA Desktop Application does not handle ICC profiles correctly or at all?

Has anyone noticed the same issue?
How about the Mac?

[CorLeone]

@CorLeone

[…] when selecting ‘Adobe RGB’ as the target color space, the file written by the stitcher has the following properties:

The color profile previously created by Lightroom has been removed – this is bad!

With the stitcher version 1.10.0 of Dec. 19, 2019, I have retested this issue: It seems to be fixed now!
I wish that Ricoh would provide more detailed information on the fixes in their release notes instead of just ‘Bug fix’!

Didn’t had time to retest the other issues yet …