Sorl-thumbnail generates black square instead of image

Question

I'm developing my project inside a Vagrant VM, the software version I'm using is:

• Ubuntu 12.04
• Django 1.6
• Sorl Thumbnail 11.12
• Pillow 2.5.3

I have some pictures in the path /var/www/django/my_project/media/icons and I have a model with an ImageField pointing to that path.

I have also THUMBNAIL_DEBUG = True in my settings.py

In my template I use thumbnail like:

{% thumbnail category.image "20" as im %}
    <img src="{{ im.url }}"></img>
{% empty %}
    {% thumbnail "png/no_image.png" "20" as im %}  # Thumbnail add the rest of the path to media
        <img id="no_image" alt="" src="{{ im.url }}" />
    {% endthumbnail%}
{% endthumbnail %}

There are some objects with image and some others without it and both shows just a black square instead of the image.

• Does anyone knows why is this happening ? I use Sorl-Thumbnail in many projects and never had this issue

I've tried to reset the full database, I used python manage.py thumbnail clear and python manage.py thumbnail cleanup

I've installed: libjpeg62 libjpeg62-dev zlib1g-dev

no_image.png is an image (red cross) not an empty image

• Am I missing any library or dependency ?

I'm lost because as I said I've worked with Sorl-thumbnail in other projects, and never saw anything like this.

Any help would be much appreciated

---

Edit

Here are some images I'm trying to display:

( I have png and jpg libraries working on Pillow )

And this is what I see in all cases:

Edit2

The problem is with the background. When I upload a png image with transparent background sorl converts the image to jpg and set the background to black...

• Is there any way to keep the transparent background or avoid conversion ?
• Is possible to set the background to white ?

I tried with:

THUMBNAIL_COLORSPACE = None
THUMBNAIL_PRESERVE_FORMAT = True

but didn't work

Studious

When you say 'black square', is that the no_image.png? When you look at the actual path being generate in the src for the image, is it pointing to the sorl thumbnail cache path (something like /media/cache/ab/fa/abf...e08.jpg) i.e. is sorl actually creating the thumbnails? – Glennaglennie

@TimmyO'Mahony The image no_image.png is a green circle and sor-thumbnail is generating the images in /media/cache/ab/... but this images are just black squares, it doesn't matter the contain on the image, sorl-thumbnail generates a black picture – Studious

Have you checked that Pillow installed with png support, ZLIB (PNG/ZIP) support available because when I used ubuntu there was problems with path to zlib1g-dev and others, so I resolved it sudo ln -s /usr/lib/x86_64-linux-gnu/libz.so /usr/lib and same for other libs, then pip install -U Pillow – Kurman

@Kurman I think the issue you're saying is for x64 machines and my machine is 32, anyways I checked Pillow installation and it says ZLIB (PNG/ZIP) support available – Studious

Do you have an example of a image that you tried to make a thumbnail of and the result? Have you set any other sorl-thumbnail related settings? – Gabriellia

@Gabriellia the issue happens with all images, I show you here 2 of them. And I allways see the black square – Studious

Works for me with your requirements. See a sample app: bitbucket.org/barseghyanartur/… – Millymilman

In settings.py is DEBUG = False? Or, do you have any normal images (not run through Thumbnail) that are showing correctly? – Bielefeld

@Bielefeld it seems the issue is with the background, sorl is changing the transparent background to black background because the png images are converted to jpg... I don't know if maybe PIL could be better than Pillow for this – Studious

Answer 1

Finally solved !

To solve the issue with the black background:

• I updated sorl-thumbnail to 12.2
• Added this 2 lines to settings.py:
  • THUMBNAIL_COLORSPACE = None
  • THUMBNAIL_PRESERVE_FORMAT = True
    
    
• Restart thumbnail database with python manage.py thumbnail clear_delete_all

Studious

I was still facing issues after this (OSError: cannot write mode P as JPEG), I ended up using these settings (since I don't care much about the image compression) THUMBNAIL_PRESERVE_FORMAT = True THUMBNAIL_FORMAT = 'PNG'. Did not change the THUMBNAIL_COLORSPACE setting (defaults to 'RGB'). – Dehisce

Answer 2

It seems like a bug in that version of sorl-thumbnail related to bad meta-data. It is currently fixed in the release candidate currently on pypi. Since pip does not install RC by default you have to specify the version to install it. Try:

pip install sorl-thumbnail==12.1c

I tried it out with the python logo and it worked fine for me with 12.1c

Gabriellia

It is weird, because actually I have almost same env: Django 1.6.7, Sorl Thumbnail 11.12, Pillow 2.5.3 except Ubuntu, I am on OS X and everything work smoothly – Kurman

It's likely that you have either PIL or Pillow installed in your system (not in the virtualenv). You could try to recreate your virtual environment with --no-site-packages option and then install Pillow. – Millymilman