• Registered: 2014-10-30
  • Posts: 2

Topic: Multi-size images support question–balancing quality and performance?

Please bear with me ...

I'm trying to create a workflow that will create a balance between image size and quality. My idea was to convert my edited original images into PNG files (sized for the Large Images parameters – the default 2048x1536) and let Juicebox create the different size jpegs when they are uploaded. That way, none of the images are are being subjected to jpeg compression more than once.

Seemed to work great for the small and medium sizes, however the large jpegs are HUGE – anywhere from 2.3 to 4.7 MBs, even when the quality setting for the large images is set as low as 55%.

When I take the largest PNG file and process it in Photoshop with 55% quality setting, I get a file that's around 550K – that's a huge difference.

Can you help me understand what's going on here?

And what are your recommendations for image sizing and processing to maintain the best balance between quality and performance?

  • Registered: 2012-04-24
  • Posts: 5,924

Re: Multi-size images support question–balancing quality and performance?

Each user will have different requirements and, in resizing images, it may help to know the target audience.
For example, if your gallery is likely to be viewed on a mobile device, then you could probably get away with having much smaller images in your gallery than if the gallery is likely to be displayed on a large desktop monitor (the content of the images and web site may play a part in determining this).
The default values in JuiceboxBuidler-Pro usually result in a good compromise between size and quality for most users (or at least a good starting point for the values to be tweaked).

Personally, I convert my own RAW images to JPEG and then feed these JPEG images to JuiceboxBuilder.
The source JPEG images are approximately 10MB each and, using the default 'Large Images' settings of 2048 x 1536 at 80%, the resulting large images are approximately 400KB each. The resulting image look good enough for me (although I understand that everyone will have their own opinion as to what is 'good enough' for their own galleries).

I do not know exactly how JuiceboxBuilder-Pro internally resizes PNG images (using whatever resizing library or algorithm that Adobe AIR provides) but the only user controls are the dimensions and quality settings.
It looks like you would have much smaller (file size) images if you worked with JPEG images from start to finish.

As long as your source images are of a high enough quality, it is unlikely that the images used in your gallery would be visually unacceptable (especially if you kept the quality setting high enough).

Otherwise, you could always create your own set of large images in Photoshop and copy them across into your gallery's 'images/large/' folder. It might be an extra step in your workflow but if it results in a gallery that you are more happy with, then it might be worth doing.