Optimal parameters for choice list reference images?

[VickiG]

Hello:

I am working on a survey that will have several different plant and tree species in choices lists.  I understand how to get reference images into the survey and it is working fine.  But the reference images are from several sources (digital, scanned film negatives) are all different file sizes, ratios, resolutions.  

I have found posts on how to constrain incoming image sizes for image questions, but was unable to find info on optimal image size/file size for reference images in choice lists.  There may not be a specific protocol for the software, but was wondering if others have had success with some parameters that a) look decent in the field app, and b) don't bog the software down with huge file sizes.

As a small aside, only one image per choice is possible, correct?  If I wanted to have tree bark and cone image for a single species reference, I would need to create a "collage" image, yes?

Thanks as always for the help!

Vicki

[Nicole_Ueberschär · Accepted solution]

Hi Vicki, I am not sure if it really helps. But I have been doing some tests with svg and jpg files. I created some quite small svg files with 200x200 pixels - they are just recognizable in the form as they are vey simple (symbolizing a range of slope), when enlarging them they get a bit blurry. The jpg seemed with 600pixels width small enough (70KB) and still big enough to be crisp when enlarged. It might depend a bit on the end device that will be used for data collection. I tried with an iphone 13s.

[VickiG]

Hi Nicole:

Thanks so much for your examples and experiences!  This gives me a ballpark idea for resizing.  I was hoping to do a bulk resize, at least on similar photo files.  I have devices from a 10in Samsung tablet to Galaxy Notes, so the bigger devices may see some degradation as you mention.

But this is definitely a great set of parameters to start with. 🙂

Thanks again!

Vicki