Strange behaviour of display colour

[Thornton]

I have just come across a phenomenon which I haven't encountered before. Using both Canon DPP and DxO PhotoLab I was processing some photos taken in an outdoor square within a shopping centre. It contains some brightly coloured light "columns" which have changing coloured patterns, containing some bright pinks and blues. The columns look as I remember them when viewed on the camera LCD and in the thumbnails in the image editors. However, when enlarged for editing the colours change to something quite different (only these columns, not the rest of the image), but then they seem to change back to normal after some seconds, although one TIFF I saved did seem to preserve the weird colour. I wonder what is going on? (The camera is set to Adobe RGB.)

[xpatUSA]

However, when enlarged for editing the colours change to something quite different (only these columns, not the rest of the image), but then they seem to change back to normal after some seconds

Julian, Some converters open with the embedded JPEG (in the raw file) showing in the review image while the raw is being converted to RGB. In that case, review images do change immediately after the conversion is complete.

I'm not convinced that's it though. When I enlarge a picture in RawTherapee it appears momentarily at very low resolution. If your apps do that too, then maybe saturated colors or out-of-gamut colors get momentarlly affected.

I wonder what is going on? (The camera is set to Adobe RGB.)

Look at an image with no columns and watch carefully for any sort of change "after some seconds".

[pschlute]

The camera is set to Adobe RGB

Are you processing raw images ? The camera setting (sRGB/AdobeRGB) will have no affect on raw files.

Are you viewing on a wide gamut monitor ?

[Thornton]

Thank you for your replies. My screen is on a laptop, so not wide gamut. I think that Ted's suggestion about out-of-gamut colours being briefly affected is probably the explanation. Having tried, as recommended, to observe carefully after opening files, I can't really see anything happening except with these particular coloured "column" shots. The "columns" are made up of some sort of light screen and display moving patterns, and the thing that is striking is the bright, unusual colours: pinks and light blues. What happens is that after displaying the colours I expect to see (presumably the embedded JPEG as suggested) the colours of the columns change very dramatically to something quite different and wrong-looking, before changing to something closer to those originally displayed. The colours in these images, leaving aside the columns, do not change in any obvious way during the time that the changes described take place.

I have just converted one of these raws to JPEG in Affinity Photo using default settings. I see now that when I open this JPEG using the Windows Pictures viewer the colours of these columns look very bright and saturated, but very shortly afterwards they change to something less saturated, but certainly I'm not seeing the weird colour shifts I see briefly inside DPP. The colours seem to increase in saturation when I magnify the image.

Julian

[xpatUSA]

Thank you for your replies.<>

I have just converted one of these raws to JPEG in Affinity Photo using default settings. I see now that when I open this JPEG using the Windows Pictures viewer the colours of these columns look very bright and saturated, but very shortly afterwards they change to something less saturated, but certainly I'm not seeing the weird colour shifts I see briefly inside DPP. The colours seem to increase in saturation when I magnify the image.

Julian, would you be able to upload that JPEG to somewhere for us to download and examine? (If only so I can irritate you by saying that my stuff does no such thing ... ...). Somewhere that stores it as-is and doesn't strip out meta-data such as EXIF would be good.

Some JPEG options cause a change when first opened. In particular the progressive option:

A progressive JPEG image is encoded differently than a standard or baseline JPEG image. It loads in successive waves until a clear picture is formed.

https://www.hostinger.com/tutorials/...ve-jpeg-images

Another JPEG option is full chroma sub-sampling (4:2:0 or 2X2) which might cause funny effects during opening in progressive mode.

I don't trust Windows-anything for viewing images ... Microsoft never did understand color-management ...

[Thornton]

Thank you Ted. I've prepared some screen shots to make viewable here. Just working on the next stage. I may be a while....

Julian

[xpatUSA]

Thank you Ted. I've prepared some screen shots to make viewable here. Just working on the next stage. I may be a while....

Julian

Good, that should demonstrate what you saw -which should help.

Is that JPEG still available? I would like to get a quick look at it too ...

[Thornton]

This is the link to a folder I've uploaded to Google Drive which contains the screenshots and also a JPEG, though I'm not sure whether the attached EXIF is available via Drive.
The photo itself was just a test shot taken when trying out a new lens I bought the other week.

The screen shots should be viewed in numerical order, which means opposite to the order they seem to have been arranged in in Drive.

I thought I'd seen peculiar colour in this photo when using DxO, but could not see it yesterday. However, I now see that the colour shift appears in DxO when the image is enlarged in the editor. It would seem that Affinity Photo doesn't display the strange colours at any point during use.

Link: https://drive.google.com/drive/folde...mt?usp=sharing

Julian

[xpatUSA]

This is the link to a folder I've uploaded to Google Drive which contains the screenshots and also a JPEG, though I'm not sure whether the attached EXIF is available via Drive.

I thought I'd seen peculiar colour in this photo when using DxO, but could not see it yesterday. However, I now see that the colour shift appears in DxO when the image is enlarged in the editor. It would seem that Affinity Photo doesn't display the strange colours at any point during use.

Link: https://drive.google.com/drive/folde...mt?usp=sharing

Julian

Thanks for the JPEG. On the column I see a grid pattern which I believe causes the effect supported by the fact that the rest of the image does not suffer. An effect appears momentarily in RawTherapee when zooming and also while moving the image:

Temporary rendition at left.



I can imagine other viewers doing something odd with that pattern ...

As to color, the EXIF says everything was in auto -so no comment about that, sorry.

[pschlute]

The "Photo with exif" file is in AdobeRGB, the rest are in sRGB. This wont be helping the analysis. I suggest you stick to sRGB

Can you post the raw file.

[Thornton]

The "Photo with exif" file is in AdobeRGB, the rest are in sRGB. This wont be helping the analysis. I suggest you stick to sRGB

Can you post the raw file.

Sorry, I hadn't realised that that photo had slipped through the net with Adobe RGB colour. I'll re-post with sRGB and also post the raw. BTW I said earlier that the screen shots I'd posted needed to be viewed in reverse order. That is clearly nonsense. The images in the previous link are in the right order, but were not when I was looking at them in my Drive folder, which is what misled me.

Julian

[pschlute]

Julian, for the raw file you will have to upload it to a dropbox account or something similar. You cannot actually "post" the raw file.

[xpatUSA]

Julian, for the raw file you will have to upload it to a dropbox account or something similar. You cannot actually "post" the raw file.

Peter, Julian is uploading his images to Google Drive which, as far I know, takes any type of file.

The color profile issue may turn out to be a red herring (!) ... especially when the red primaries of sRGB and Adobe RGB (1998) are the same CIE color.

[pschlute]

Peter, Julian is uploading his images to Google Drive which, as far I know, takes any type of file.

The color profile issue may turn out to be a red herring (!) ... especially when the red primaries of sRGB and Adobe RGB (1998) are the same CIE color.

Ah yes, I forgot I downloaded them from there !

Yes , or indeed a green herring (!). But it does make sense to keep any jpegs in the same colour space.

[Manfred M]

Based on the description, I wonder if all that Julian is seeing is the screen refreshing as the software rebuilds the image from the raw data.