JPG compatibility problem

[RobsBlack]

Hello everyone, I hope you can help me. I have an old Canon Selphy CP750 printer. If I try to create a JPG image to print, the image is not recognized as a valid JPG. I attach both an old working image (image-ok.jpg) and one with problems (image-not-working.jpg). They are gray demo images. I hope you can help me understand the difference and how to generate compatible JPG images with Affinity. Thank you!

 

 

 

img.zip

Edited May 4 by RobsBlack

[thomaso]

Hi @RobsBlack, Welcome to the Affinity Forums!

When adding an image file a web browser can display the forums software may strip some EXIF metadata, remove the colour profile and recompress the image. To avoid this you need to add the attachments within a ZIP file. You might be able to edit your recent post + add a ZIP file containing the two images + remove the current JPG files from the post (in the area below your post). If you are not allowed as new forums member yet to edit your post you can add the ZIP in a new post.

Also, what app does report the error? Can you post a screenshot of the message, including a hint to its app name (e.g. menu bar), and additionally mention your platform/OS version and Affinity app + version?

[RobsBlack]

Hi @thomaso, thanks for your help. I added the zip file. I have no information on the error because I print the image via SD Card. A question mark simply appears on the printer display and does not allow me to print the image. I think it's a difference in the JPG format but I can't figure out exactly what.

 

Affinity windows version: 2.4.2

 

Edited May 4 by RobsBlack

[NotMyFault]

Unfortunately there are many JPEG file format versions, incompatible to each other:

https://en.wikipedia.org/wiki/JPEG#JPEG_files

You can try to inspect metadata e.g. with exif tool to find out the difference between your files 

[Return]

I had no problems opening your files but like @NotMyFault said there are multiple formats which nowadays use the jpeg extension but may be a different file under the hood.
I tend to use xnviewmp to watch the files and use it's batch converter to convert it to another format.

[Alfred]

37 minutes ago, RobsBlack said:

I print the image via SD Card

The SD card’s file system may be imposing restrictions that are getting in the way. Do you have any other options such as printing wirelessly or via a USB cable?

[thomaso]

38 minutes ago, RobsBlack said:

I print the image via SD Card. A question mark simply appears on the printer display and does not allow me to print the image.

So the printer's software (from ~2007) seems to be the bottleneck. – Did you transfer both images to the printer from the same SD-Card (same formatting)?

Exiftool reports various different entries but I don't see any obvious which may matter. They differ for instance in:

"Exif Byte Order":
• not-working.jpg: Big-endian (Motorola, MM)
• ok.jpg: Little-endian (Intel, II)

Also the ok.jpg has an entry "Compression: JPEG (old-style)" / the not-working has no compression entry.

Possibly the different encoding is an issue for this old printer (~2007)? In the linked thread (12 years old) a user had issues when displaying a JPG that has been created in Windows 7 but not if in XP – and the solution appeared to be to change the "Exif Byte Order" via Exiftool:

https://stackoverflow.com/questions/7177781/how-does-jpeg-endianness-matter-on-coding

[RobsBlack]

Thank you all! I'll do some testing and let you know if I can solve it.

[David in Яuislip]

Try this file, if it works the command  is

exiftool -exif:all= -tagsfromfile @ -exif:all -ExifByteOrder=II img-not-working.jpg

For more info see Exiftool help, faq20 under advanced

img-not-workingNew.zip

[David in Яuislip]

On 5/4/2024 at 1:34 PM, RobsBlack said:

A question mark simply appears on the printer display

This may be because there is no thumbnail embedded. Try again with that option ticked in Preferences, then run the above exiftool command and see if that's printable

Otherwise download Canon's DPP program and run your Affinity exports through that

[RobsBlack]

@David in Яuislip  you found the solution! Thank you very much! The problem was the thumbnail which was not embeeded. I generated a smaller jpg (160x108 px) and embeeded it in the image with exiftool. And it worked now the image is seen on the printer screen and is printed correctly. I didn't understand how to integrate the thumbnail from Affinity but anyway I found a way to still use my old printer. So thank you! And thanks to everyone who responded to help me!