Can't read metadata data (EXIF) information in JPEG files #84661

New Issue

Charles Semeon · 2021-01-13T05:45:54+01:00

Charles Semeon commented

2021-01-13 05:45:54 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2070 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67

Blender Version
Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: 0f45cab862
Worked: (newest version of Blender that worked as expected)

Short description of error
A bit of context first, I setup a Node group that helps me scale textures to real world scale. So I use the images DPI or PPM for this. Thus I scripted the inputs for the Node groups to automatically grab the relevant information.

It works fine with PNG and TIF but not with JPEG. I use the script below to gather the DPI. For JPEGs, I get the wrong DPI, 72 dpi (2834.646 ppm). Even if the correct value should be higher, blender always displays 72dpi.

To overcome this, I added a python module ExifRead. There are others. This was arbitrary.
Now, I have the function to gather the correct DPI. Except it complicates the code... :)

Also, don't know if its my environment (work office) that is the issue, firewall and etc... I could not install the module over the internet using the pip function in python. I had to install using the wheel file. not a major issue.

Exact steps for others to reproduce the error

Download the attached image or create one yourself with a DPI higher than 72
Load the image in Blender

Run `bpy.data.images["300dpi.jpg"].resolution`

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce RTX 2070 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67 **Blender Version** Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: `0f45cab862` Worked: (newest version of Blender that worked as expected) **Short description of error** A bit of context first, I setup a Node group that helps me scale textures to real world scale. So I use the images DPI or PPM for this. Thus I scripted the inputs for the Node groups to automatically grab the relevant information. It works fine with PNG and TIF but not with JPEG. I use the script below to gather the DPI. For JPEGs, I get the wrong DPI, 72 dpi (2834.646 ppm). Even if the correct value should be higher, blender always displays 72dpi. To overcome this, I added a python module ExifRead. There are others. This was arbitrary. Now, I have the function to gather the correct DPI. Except it complicates the code... :) Also, don't know if its my environment (work office) that is the issue, firewall and etc... I could not install the module over the internet using the pip function in python. I had to install using the wheel file. not a major issue. **Exact steps for others to reproduce the error** - Download the attached image or create one yourself with a DPI higher than 72 - Load the image in Blender # Run `bpy.data.images["300dpi.jpg"].resolution` ![300dpi.jpg](https://archive.blender.org/developer/F9562726/300dpi.jpg)

Charles Semeon commented

2021-01-13 05:45:54 +01:00

Added subscriber: @CharlesSemeon

Robert Guetzkow commented

2021-01-13 10:45:43 +01:00

Added subscriber: @rjg

Robert Guetzkow commented

2021-01-13 10:45:43 +01:00

It seems that this isn't set for JPEG. In a cursory search in the source code only *.png, *.exr, *.tif and *.bmp seem to set the ppm on the ibuf which is used for the resolution property. From my current understanding this is a missing feature, but given that the Python API doesn't indicate that the resolution may not have been loaded from the files metadata, this could also be considered a bug.

It seems that this isn't set for JPEG. In a cursory search in the source code only *.png, *.exr, *.tif and *.bmp seem to set the `ppm` on the `ibuf` which is used for the `resolution` property. From my current understanding this is a missing feature, but given that the Python API doesn't indicate that the `resolution` may not have been loaded from the files metadata, this could also be considered a bug.

blender-admin commented

2021-01-21 16:13:30 +01:00

This issue was referenced by 6f88053d85

This issue was referenced by 6f88053d852ad7f04b3d67b1905d88917f481ee3

Philipp Oeser commented

2021-01-21 16:25:25 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-01-21 16:25:25 +01:00

D10166 looks like it does the trick, not 100% sure though.

[D10166](https://archive.blender.org/developer/D10166) looks like it does the trick, not 100% sure though.

Philipp Oeser commented

2021-01-21 16:27:59 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2021-01-21 16:27:59 +01:00

Since we have a patch, will confirm for now.

Philipp Oeser commented

2021-01-29 11:37:55 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Philipp Oeser closed this issue

2021-01-29 11:37:55 +01:00

Philipp Oeser self-assigned this 2021-01-29 11:37:55 +01:00

Charles Semeon commented

2021-02-03 06:28:39 +01:00

Hello, I am not sure it this is the place for me to post update on the issue.

I was a happy bunny when this was resolved but it does not work on all JPEGs.

I attached the image that does not retrieve the DPI. Also, to make it work I have to re-save in another program (irfan view) when I re-save in Photoshop the problem persist.

Hello, I am not sure it this is the place for me to post update on the issue. I was a happy bunny when this was resolved but it does not work on all JPEGs. I attached the image that does not retrieve the DPI. Also, to make it work I have to re-save in another program (irfan view) when I re-save in Photoshop the problem persist. ![RED 300dpi.jpg](https://archive.blender.org/developer/F9610197/RED_300dpi.jpg)

Philipp Oeser commented

2021-02-03 07:20:44 +01:00

Changed status from 'Resolved' to: 'Needs Triage'

Philipp Oeser reopened this issue

2021-02-03 07:20:44 +01:00

Philipp Oeser commented

2021-02-03 09:05:14 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philipp Oeser commented

2021-02-03 09:05:14 +01:00

Had a look and in contrast to 300dpi.jpg [which has its density_unit set to 1 correctly -- 1 corresponds to dots/inch], the other file you provided RED_300dpi.jpg has its density_unit set to 0 [0 corresponds to 'unknown'].
In case of 'unknown', there is not much we can/should do?

If I resave RED_300dpi.jpg from Gimp, it then has its density_unit set correctly to 1.

Does this help possibly?
https://community.adobe.com/t5/photoshop/how-to-export-a-jpeg-with-300dpi-ps-keeps-exporting-at-96dpi-even-though-image-res-is-set-to-300px/td-p/8146131

Had a look and in contrast to `300dpi.jpg` [which has its `density_unit` set to 1 correctly -- 1 corresponds to dots/inch], the other file you provided `RED_300dpi.jpg` has its `density_unit` set to 0 [0 corresponds to 'unknown']. In case of 'unknown', there is not much we can/should do? If I resave `RED_300dpi.jpg` from Gimp, it then has its `density_unit` set correctly to 1. Does this help possibly? https://community.adobe.com/t5/photoshop/how-to-export-a-jpeg-with-300dpi-ps-keeps-exporting-at-96dpi-even-though-image-res-is-set-to-300px/td-p/8146131

Charles Semeon commented

2021-02-03 11:41:53 +01:00

Thanks for the reply.

The adobe community page does not solve the problem. Adobe still doesn't save with a density unit of 1.

So I will have to put warning signs to not use JPEGs in the setup. :)

Thanks for the reply. The adobe community page does not solve the problem. Adobe still doesn't save with a density unit of 1. So I will have to put warning signs to not use JPEGs in the setup. :)

Philipp Oeser commented

2021-02-05 12:53:10 +01:00

Changed status from 'Needs User Info' to: 'Resolved'

Philipp Oeser closed this issue

2021-02-05 12:53:10 +01:00

Philipp Oeser commented

2021-02-05 12:53:10 +01:00

Hi @CharlesSemeon .

This is a bit unfortunate, but I guess there is really not much we can do here.
Sorry to say, but will close again.
If you get any updates fro the Adobe side (or other information that would let us proceed on our side, please let us know!)

Hi @CharlesSemeon . This is a bit unfortunate, but I guess there is really not much we can do here. Sorry to say, but will close again. If you get any updates fro the Adobe side (or other information that would let us proceed on our side, please let us know!)

Charles Semeon commented

2021-03-09 06:48:42 +01:00

Hello Philipp,

Not much of an update. Below is an answer I got from the Adobe community.

There are two different JPEG metadata containers, EXIF and JFIF. Many files contain elements from both, but you need to handle both formats. I use JPEGLib to parse JPEG files. I cannot suggest any Python solution, that's not my area. https:*en.wikipedia.org/wiki/JPEG_File_Interchange_Format

I tried to prove the information by looking for modules that can read JFIF. BUT I can not advance enough for this. I'll just stick to moving vertices.... :)

Hope this helps.

Regards,
Charles

Hello Philipp, Not much of an update. Below is an answer I got from the Adobe community. > There are two different JPEG metadata containers, EXIF and JFIF. Many files contain elements from both, but you need to handle both formats. I use JPEGLib to parse JPEG files. I cannot suggest any Python solution, that's not my area. [https:*en.wikipedia.org/wiki/JPEG_File_Interchange_Format](https:*en.wikipedia.org/wiki/JPEG_File_Interchange_Format#:~:text=Xthumbnail%20%C3%97%20Ythumbnail-,Compatibility,immediately%20follow%20the%20SOI%20marker) I tried to prove the information by looking for modules that can read JFIF. BUT I can not advance enough for this. I'll just stick to moving vertices.... :) Hope this helps. Regards, Charles

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Can't read metadata data (EXIF) information in JPEG files #84661

Run bpy.data.images["300dpi.jpg"].resolution

Run `bpy.data.images["300dpi.jpg"].resolution`