I’m setting up Nextcloud as my private Google Photos replacement. I am still researching the compression algorithm to use (though I don’t have the horsepower needed for Google’s Guetzli), but my current issue stands with Nextcloud’s preview generation, and lack of documentation.
As I understand from this single online article I’ve been able to find that attempts to describe some of the Preview Generator’s options, previews of several dimensions are generated:
- 32x32 images are supposedly thumbnails for the Files app in “List view”;
- 256×256 images get generated three times, to my understanding: First, as thumbnails for the Files app in “Grid view”, and then twice for the Gallery app, once as regular thumbnails and once as folder thumbnails;
preview_max, which is actually the image that gets displayed when a user opens an image, instead of the original file. By default, this can be up to 16MP!
I would like to save space and computing power by reducing the number of previews that get generated. I am okay with 32x32 thumbs, but I would not like 3 different thumbnails generated for images in the 256×256 size – where and how can I force the Preview Generator to only create one image that both the Files and Gallery app can use?
Lastly, my biggest complaint is with the
preview_max (or max preview) image. It takes up considerable disk space and processing power to generate them, but is ultimately useless to me as an end user – If my images are compressed and optimized for size already, why can’t the server show me the original (optimized) photo instead of bogging down the server to generate an image which is of lower quality? (In Google Photos, the image that gets displayed in full screen is the largest resolution image available – No need to download the image to get the full resolution pic.)