Allow to override the image toolkit's global JPEG/PNG quality value

This is exactly what i wanted to do before starting the search to check if anybody already thought about that.
A good example/usecase for that are overview pages like this: http://www.texturecase.com/texturen/holz

As far as i can see, adding that to 7.x would not break api (for other modules that use this api). But i am not so advanced with architectural stuff. So whats the opinion of the core developers?

manually applied it and also tested your image quality module. works fine here.

ok this patch breaks, that the correct quality setting is used, from the toolkit page where you set jpeg quality

it changes image.gd.inc line 272

//$success = $function($image->resource, $destination, variable_get('image_jpeg_quality', 75));
$quality = variable_get('imageapi_jpeg_quality', 75);

seems this uses an old d6 variable from the imageapi.

correct:

$quality = variable_get('image_jpeg_quality', 75);

i fixed the above patch and attached it.

Nope, that's a non-starter.

The image toolkit must not have any knowledge of the Image module and its image styles. The image toolkit API only cares for 1) pluggable toolkits, and 2) performing actions on an image resource.

Let's actually go one step further and not only allow to override it, but also allow to adjust the quality in an Image style.

The latter is only a few lines of code, so I don't see any reason for why that shouldn't be directly in core.

Image quality can also be used for PNG, but should then be split in the quality/10 for compression and quality % 10 for filter.

I based my comment on http://www.imagemagick.org/Usage/formats/#png_quality, but I see it is specified different in GD. So if this is going to be cross toolkit, we need to come up with a UI that hides the differences. In my opinion this should be an effect that can be added anywhere in the list to a style and that then overrides the default setting. See e.g. the change image format effect of imagecache_actions that also contains a quality parameter (which is used as is, thus no good UI).

re #13: The need to override forms is tricky. Currently, you are able to change toolkit without having to change the parameters of existing image style effects. So the effects should be geared towards what is possible with images and image formats, not how a specific toolkit implements it.

My idea is that with the default settings (admin/config/media/image-toolkit) we get:
- 1 field for the default jpeg quality (currently existing, 0-100%)
- 1 field for the default png compression (0-9, default 6)
- 1 field for the default png filter (none, sub, up, avg, Paeth, adaptive/all, single valued drop-down value, thus no bitmask, default adaptive)
- The code should not use the GD constants, these may be not available...it may, of course. use the same values so that no lookup conversion is needed for the GD tookit.

The new to create quality effect should offer the same fields.

+++ b/core/modules/image/image.admin.incundefined
@@ -453,6 +453,32 @@ function image_effect_scale_validate($element, &$form_state) {
+      if ($value == 8 && $count > 1 || $value == 248 && $count > 1) {

You better add parenthese to express what you mean. I think the expressions is wrong. It can also be simplified, as the science of logic teaches us that (a and c) or (b and c) <=> (a or b) and c

+++ b/core/modules/image/image.admin.incundefined
@@ -453,6 +453,32 @@ function image_effect_scale_validate($element, &$form_state) {
+        form_error($element, t("The options 'None' or 'All' can only be applied on its own", array('!name' => $element['#title'])));

For words that need to be translated anyway, I prefer to pass them in as a param. It is better to keep them equal.

+++ b/core/modules/image/image.admin.incundefined
@@ -584,6 +610,97 @@ function image_rotate_form($data) {
+  // To make it consistent with the JPEG quality option, this dropdown is for
+  // setting the quality rather than the compression level. The scale of
+  // 1 (lowest) - 10 (highest) is used.
+  $form['png']['compression'] = array(
+    '#type' => 'select',
+    '#title' => t('Quality'),
+    '#default_value' => isset($data['png']['compression']) ? $data['png']['compression'] : 4,
+    '#required' => TRUE,
+    '#options' => $image_quality_options['compression'],
+    '#multiple' => FALSE,
+    '#description' => t('Define the image quality for PNG manipulations. Ranges from 1 to 10. Higher values mean better image quality but bigger files.'),
+  );

This is thus wrong: higher compression means same quality (png is lossless), lower file size but increased generation time.

+++ b/core/modules/image/image.admin.incundefined
@@ -849,3 +966,39 @@ function theme_image_rotate_summary($variables) {
+  $summary = t('JPEG: ') . $data['quality'] . '%; ';

JPEG (and further on PNG) are probably not translated in and by themselves. What may be translated though is the word order, so I think that the whole sentence should be 1 translatable string (with a numeric parameter).

In French e.g, you normally add a space before a colon.

+++ b/core/modules/image/image.effects.incundefined
@@ -312,3 +320,28 @@ function image_rotate_dimensions(array &$dimensions, array $data) {
+ */
+function image_quality_effect(&$image, $data) {
+	$image->quality = $data['quality'];
+	$image->filter = $data['png']['filter'];
+	$image->png_quality = $data['png']['compression'];
+	return TRUE;
+}

function image_quality_effect contains tabs instead of spaces as do the changes in function image_gd_save.

That's it for now. I didn't look at it as a whole yet, just function by function. Nor about if and how to add tests.

Hello,

is there a patch for Drupal 7? Patchs in this post are for Drupal 8 and 6.

Thank you.

Will certainly need a reroll (rewrite). But as I created a related issue that might ease the task of writing a patch for this, I suggest to focus on that one first. Deleted incorrect tags.

Here is the reroll.

You are adding back old code. The image style/effect system has been moved to classes and plugins. Strange though. that it passes all tests, but probably you are adding in lots of untested code.

I propose to first wait on the related issue #2168511: Allow to pass save options to ImageInterface::save and then give this one a new try. So, if you could review the other issue and have that one get in first, this one becomes easier to (re)write.

It is unfortunate that this has been postponed for so many years. This is not just a performance issue for websites, it is an equity issue for site visitors who have limited data plans, commonly on mobile devices.

Adding Social Equity tag. This issue presents a social equity issue because its lack leads to more data being downloaded than necessary, which can have an economic cost for people who are charged for their internet service based on the amount of data they download.