Storage: Image quality transformation is respected for createSignedUrl() but not for download()

[pdurasie]

Describe the bug
For supabase storage, when you use transform params together with quality parameter in the download method, the returned image will respect the height and width params but ignore the quality. In other words, no matter whether you pass in quality: 20 or quality: 100, the returned image will be the same.

Additionally, the image will be returned in PNG even though WebP would be expected, as I'm working with Flutter Web (Chrome), but this might be a separate issue with Automatic image optimization.

To Reproduce
Steps to reproduce the behavior:

1. Upload a PNG image to a bucket
2. Run this in Flutter Web (Chrome) and check the file size, dimensions and image quality in Chrome DevTools

await supabase.storage.from('my-bucket').download(
          'my_img.png',
          transform: const TransformOptions(
            height: 840,
            width: 480,
            quality: 100,
          ),
        );

3. Clear cache and run this in Flutter Web (Chrome) and check the file size, dimensions and image quality in Chrome DevTools

await supabase.storage.from('my-bucket').download(
          'my_img.png',
          transform: const TransformOptions(
            height: 840,
            width: 480,
            quality: 20,
          ),
        );

You will see that the downloaded images in 2. and 3. will be PNG, identical file size, of dimensions 480x840 and 100% quality.

Expected behavior
The downloaded images should differ in file size and quality (and be WebP).

Version (please complete the following information):
├── supabase_flutter 2.3.2
│ ├── supabase 2.0.7
│ │ ├── functions_client 2.0.0
│ │ ├── gotrue 2.5.0
│ │ ├── postgrest 2.1.0
│ │ ├── realtime_client 2.0.0
│ │ ├── storage_client 2.0.1

Additional context
Using the same parameters to createSignedUrl and then pasting that URL into Chrome does affect the returned image as expected (different quality and WebP).

I have not tested mobile.

I have not tested other image formats but PNG.

[wemgl]

Any workaround for this yet? I've run into this issue and all the images that I download show up blurred in my flutter app.

[dshukertjr]

@wemgl Apologies for taking time to getting to this one.

The format not being webp is expected, as you are not making the HTTP request from the browser's image component, but rather manually sending an HTTP request through the download() method, so let's focus on just the quality issue on this thread.

Although the quality not being respected when using the download() method is concerning, I want to break down why you are downloading the image in the first place. Are you simply displaying the image in your app, or do you actually need to download the image to do something more than just displaying them?

I download show up blurred in my flutter app

So now the image not only ignores the quality parameter, but also is modified to be blurred?