The screen to configure the new feature multiple size contains far too many options to be usable by humans (in my opinion). It shows all what Piwigo can do but it doesn't help the user. Here is what I propose and questions related to implied changes:

1) we remove the sharpen parameter. Very useful for GD (any other value than 0 breaks image generation with ImageMagick) but too complicated for users. I think we'd better hardcode a default setting (this is what I did with ImageMagick since Piwigo support ImageMagick)

2) by default we don't display dimensions as form fields but as summary :

[x] XXS - tiny cropped 240x240, [change settings]
[x] XS - very small, 432x324, [change settings]
[ ] S - small

Size disabled = no settings summary

When you click on the "change settings" links, it show the form fields :

[x] [b]XXS - tiny[/b] cropped 240x240, [link: change settings]
  [x] Crop
  Width
  [240 ]
  Height
  [240 ]

[x] [b]XS - very small[/b], 432x324, [link: change settings]
  [] Crop
  Maximum width
  [432 ]
  Maximum height
  [324 ]

If you check the "crop" option, "Maximum width" becomes "Width".

I've played with the current width, height, crop(%), min width, min height and I haven't been able to understand the way these settings were working altogether :-/ I mean for example an crop 45% and a width != min width. I think that the ergonomy we had worked on with P@t was quite simple and understandable.

This ergonomy is equal to a crop 100% and width=minWidth and height=maxHeight in the new system. Maybe it's less possibilities for users but at least they can configure their gallery and expect the behavior they want.

The problem with these changes is that there won't be an "easy way" to use Piwigo settings at full capacity without generating something like :

$conf['derivatives_custom'] = ' a:3:{s:1:"d";a:9:{s:6:"square";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:120;i:1;i:120;}s:8:"max_crop";d:1;s:8:"min_size";a:2:{i:0;i:120;i:1;i:120;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:5:"thumb";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:144;i:1;i:144;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:6:"2small";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:1333373332;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:240;i:1;i:145;}s:8:"max_crop";d:1;s:8:"min_size";a:2:{i:0;i:240;i:1;i:145;}}s:7:"sharpen";i:0;s:7:"quality";i:95;}s:6:"xsmall";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:432;i:1;i:324;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:5:"small";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:576;i:1;i:432;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:6:"medium";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:1333225678;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:792;i:1;i:594;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:95;}s:5:"large";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:1008;i:1;i:756;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:6:"xlarge";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:1224;i:1;i:918;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}s:7:"xxlarge";O:16:"DerivativeParams":4:{s:13:"last_mod_time";i:0;s:6:"sizing";O:12:"SizingParams":3:{s:10:"ideal_size";a:2:{i:0;i:1656;i:1;i:1242;}s:8:"max_crop";d:0;s:8:"min_size";a:2:{i:0;i:0;i:1;i:0;}}s:7:"sharpen";i:0;s:7:"quality";i:85;}}s:1:"w";O:15:"WatermarkParams":6:{s:4:"file";s:0:"";s:8:"min_size";a:2:{i:0;i:500;i:1;i:500;}s:4:"xpos";i:50;s:4:"ypos";i:50;s:7:"xrepeat";i:0;s:7:"opacity";i:100;}s:1:"c";a:0:{}}';

Which is highly unreadable of course.

rvelices, how do you see a "full possibilities" settings system for derivatives while keeping an "easy to understand" user interface?