Some images not presenting in Safari

Online experiments
1

URL of experiment: JBT_Familiarity_Online [PsychoPy]

Description of the problem:

Hi all,

I have a study where participants view a bunch of images and then make a judgement. I launched this study a week ago and discovered today that in Safari only some of the images are shown to the participant. I am attaching two screenshots at the end of this post.

Here is what I did so far:
Changed the file type of the images
Checked the web console to make sure the image is getting loaded on the screen
Checked other browsers: Mozilla and Chrome do not have issues.

Also, I am not certain about this, but I don’t think there is consistency in which images show up.

Any ideas or thoughts on how to solve this or mitigate it?

Thanks
Balbir Singh

Screen Shot 2020-09-25 at 2.33.56 PM
Screen Shot 2020-09-25 at 2.33.56 PM512×649 65.9 KB

Screen Shot 2020-09-25 at 2.33.51 PM
Screen Shot 2020-09-25 at 2.33.51 PM593×674 4.71 KB

2

Hi Balbir,

I’m the PsychoJS tester and I happen to be planning to run some large-scale tests of image presentation next week (run it on 100+ devices). I’d love to try out your picture set to see if I can reproduce the issue. Two questions:

  • Could you make you experiment public on GitLab and share the link (or make me a collaborator)? Then I can grab your pictures and plug them in my tests.
  • What version of MacOS have you been testing on?

Best, Thomas

3

Hi Thomas,

That sounds great! Here is the gitlab link: https://gitlab.pavlovia.org/bsingh/jbt-familiarity-online-study-1

I am using Catalina 10.15.6

Balbir Singh

4

I found a solution that works for my specific study, but may or may not answer why this occurred.

Originally the images were bitmaps. I got them from another researcher and figured if Pavlovia can support the bitmap file format it should be fine. Before I posted on the forum, I converted the bitmap files to pngs using Finder. While my mac recognized the change, I don’t think Safari recognized it.

Here is how I fixed the issue. I opened each image in GIMP and exported them as jpgs. I then went through each image and changed the permissions to be ‘read and write’ for everyone.

After syncing the study to Pavlovia, the images now present properly in Firefox, Chrome and Safari.

@thomas_pronk I removed the problematic images from this study, so my participants don’t have to suffer through extra loading time. If you still want to test the old images, I can upload them in a different project.

5

Thanks for the update! Yes, that could explain it. If I get you right the method via Finder was renaming the files to PNG but not encoding them in to PNG?

6

Yes, Finder seemed to be recognizing the renamed files as PNG, but I don’t think the encoding actually changed.

7

Very clear. Thanks for clarifying that!