[wp-trac] [WordPress Trac] #40415: Imagick resize filter hook

[WordPress Trac]

#40415: Imagick resize filter hook
-------------------------------------+---------------------
 Reporter:  virgodesign              |       Owner:  (none)
     Type:  enhancement              |      Status:  new
 Priority:  normal                   |   Milestone:  5.0
Component:  Media                    |     Version:  4.7.3
 Severity:  normal                   |  Resolution:
 Keywords:  has-patch needs-testing  |     Focuses:
-------------------------------------+---------------------
Changes (by audrasjb):

 * keywords:  has-patch => has-patch needs-testing
 * milestone:  Awaiting Review => 5.0


Old description:

> As of ticket #33642, Wordpress 4.5 introduces the `thumbnail_image()`
> function within the `WP_Image_Editor_Imagick` class.
> This function uses the default imagick filter `FILTER_TRIANGLE` to
> assists the image resizing process.
> Within the `thumbnail_image()` is even declared a list of allowed filters
> that actually are absolute unsued due to the fact that wordpress uses
> only the default filter `FILTER_TRIANGLE`. The filter list is
>
> {{{
> 'FILTER_POINT'
> 'FILTER_BOX'
> 'FILTER_TRIANGLE'
> 'FILTER_HERMITE'
> 'FILTER_HANNING'
> 'FILTER_HAMMING'
> 'FILTER_BLACKMAN'
> 'FILTER_GAUSSIAN'
> 'FILTER_QUADRATIC'
> 'FILTER_CUBIC'
> 'FILTER_CATROM'
> 'FILTER_MITCHELL'
> 'FILTER_LANCZOS'
> 'FILTER_BESSEL'
> 'FILTER_SINC'
> }}}
>
> Resizing image using the default filter often gives as a result a softly
> blurry thumbnail image. this blur effect became more visible as the
> thumbnail size increase.
>
> Using filter like `FILTER_HAMMING` or `FILTER_SINC` the blur effect
> disappear, giving a great resizing result.
>
> To better improve the use of the resizing process and to give any users
> the ability to choose which type of filter to use, I think that could be
> implemented the following filter hook:
>
> {{{
> $filter_name = apply_filters('image_resize_filter', $filter_name);
> }}}
>
> that will give an opportunity to change this filter before the resizing
> process will perform.
> This filter should be implemented at the beginning (line 1) of the
> `thumbnail_image()` function.
> This way everyone can, optionally, change the imagick resize filter
> easily.

New description:

 As of ticket #33642, WordPress 4.5 introduces the `thumbnail_image()`
 function within the `WP_Image_Editor_Imagick` class.
 This function uses the default imagick filter `FILTER_TRIANGLE` to assists
 the image resizing process.
 Within the `thumbnail_image()` is even declared a list of allowed filters
 that actually are absolute unsued due to the fact that wordpress uses only
 the default filter `FILTER_TRIANGLE`. The filter list is

 {{{
 'FILTER_POINT'
 'FILTER_BOX'
 'FILTER_TRIANGLE'
 'FILTER_HERMITE'
 'FILTER_HANNING'
 'FILTER_HAMMING'
 'FILTER_BLACKMAN'
 'FILTER_GAUSSIAN'
 'FILTER_QUADRATIC'
 'FILTER_CUBIC'
 'FILTER_CATROM'
 'FILTER_MITCHELL'
 'FILTER_LANCZOS'
 'FILTER_BESSEL'
 'FILTER_SINC'
 }}}

 Resizing image using the default filter often gives as a result a softly
 blurry thumbnail image. this blur effect became more visible as the
 thumbnail size increase.

 Using filter like `FILTER_HAMMING` or `FILTER_SINC` the blur effect
 disappear, giving a great resizing result.

 To better improve the use of the resizing process and to give any users
 the ability to choose which type of filter to use, I think that could be
 implemented the following filter hook:

 {{{
 $filter_name = apply_filters('image_resize_filter', $filter_name);
 }}}

 that will give an opportunity to change this filter before the resizing
 process will perform.
 This filter should be implemented at the beginning (line 1) of the
 `thumbnail_image()` function.
 This way everyone can, optionally, change the imagick resize filter
 easily.

--

Comment:

 Hi!

 I'd say we also need to add `FILTER_HAMMING` to default filter fallback :)

 Cheers,
 Jb

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/40415#comment:3>
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