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16-bit grayscale TIFF is opened as 8-bit RGB

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When I tried to open 16-bit grayscale TIFF files in Affinity Photo (Mac), they are always opened as 8-bit RGB. Is there any way to force opening as 16-bit grayscale?

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Your TIF file has no EXIF information, and thus no color profile information embedded in it. That means that Affinity Photo has no way to know it's grayscale, and therefore it assigns a standard RGB profile to it.


-- Walt

Windows 10 Home, April 2018 Update (1803), 16.0GB memory, Intel Core i7-6700K @ 4.00Gz
Affinity Photo 1.6.4.104 and 1.6.5.112 Beta
Affinity Designer 1.6.4.104 and 1.6.5.112 Beta

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1 hour ago, walt.farrell said:

Your TIF file has no EXIF information, and thus no color profile information embedded in it. That means that Affinity Photo has no way to know it's grayscale, and therefore it assigns a standard RGB profile to it.

The TIFF file actually contains ample EXIF information, it's the photometric model that is stopping Affinity Photo from recognising its format correctly.

@icetype, the software (or device) that produces the TIFFs you're working with sets the photometric interpretation to "white is zero". Most TIFFs are either "RGB" (full colour) or "black is zero" (bilevel/greyscale). I've changed the EXIF tag, imported the TIFF and inverted it—it's attached to this post. Could you open it and make sure it's correct? If so, I can give you a workaround for now, but I'll also log it with the developers. Hope that helps!

16bitGray copy.tif


More than 200 Affinity Photo Video Tutorials - Affinity Photo for iPad Tutorials

Looking for a manual/documentation? Check affinity.help for online help!

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Dear Walt and James,

Thank you for the valuable information and inputs. I really wish there is a way to "tell" Affinity Photo that it is grayscale upon opening. I can manually change the color format after loading, but then the image has already lost the gray level resolution.

Photoshop, Image J and GIMP etc. can somehow correctly recognize it as 16-bit grayscale.

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3 minutes ago, icetype said:

Thank you for the valuable information and inputs. I really wish there is a way to "tell" Affinity Photo that it is grayscale upon opening. I can manually change the color format after loading, but then the image has already lost the gray level resolution.

There is a workaround by changing an EXIF tag, I posted an explanation above—it maintains the 16-bit format and correctly assigns a greyscale colour profile, so you don't lose any precision. If you can verify that my attached TIFF file opens as a 16-bit greyscale document (so it actually works for you) I can detail the instructions. This would enable you to use Affinity Photo in the interim before the issue is fixed.


More than 200 Affinity Photo Video Tutorials - Affinity Photo for iPad Tutorials

Looking for a manual/documentation? Check affinity.help for online help!

@JamesR_Affinity for tutorial sneak peeks and more

500px for photography edited in Affinity Photo

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Dear James,

Yes, I could verify that the TIFF file you attached (16bitGray copy.tif) can be correctly opened as 16-bit grayscale in both Affinity Photo and Affinity Designer. Detailed instructions will be truly appreciated. 

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17 minutes ago, James Ritson said:

The TIFF file actually contains ample EXIF information, it's the photometric model that is stopping Affinity Photo from recognising its format correctly

Thanks, James. Interesting; according to IrfanView (or my interpretation of what it's telling me) there's no EXIF info, so I'll have to look at that again.


-- Walt

Windows 10 Home, April 2018 Update (1803), 16.0GB memory, Intel Core i7-6700K @ 4.00Gz
Affinity Photo 1.6.4.104 and 1.6.5.112 Beta
Affinity Designer 1.6.4.104 and 1.6.5.112 Beta

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16 minutes ago, walt.farrell said:

Thanks, James. Interesting; according to IrfanView (or my interpretation of what it's telling me) there's no EXIF info, so I'll have to look at that again.

Hmm, that's interesting—both Photo and exiftool can read the metadata...

@icetype, you can use any software that will modify EXIF data. I've used exiftool (https://www.sno.phy.queensu.ca/~phil/exiftool/install.html) but you could apply these instructions to other software.

You'll want to change the tag called "PhotometricInterpretation" to "BlackIsZero" or "1". To do this in exiftool, for example, you would type:

exiftool -PhotometricInterpretation="BlackIsZero" "path/to/file.tif"

Replace "path/to/file.tif" with your TIFF file (in both Windows and macOS I believe you can just click-drag the file onto the command prompt/terminal window)

Now load the file into Affinity Photo. It will assign a greyscale D50 profile and the bit depth should still be 16bpc. Now just go to Layer>Invert (since we reversed the photometric model) to see your image as intended.

Note that if you're using other software to modify the EXIF tags, it might be using friendly names—so you'd just look for Photometric Interpretation with a space rather than as one word.

Hope that helps!


More than 200 Affinity Photo Video Tutorials - Affinity Photo for iPad Tutorials

Looking for a manual/documentation? Check affinity.help for online help!

@JamesR_Affinity for tutorial sneak peeks and more

500px for photography edited in Affinity Photo

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Dear James,

Thank you very much for the instruction and it worked beautifully! I think I can use the workaround for now. Hopefully the developers will implement it in the near future.

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