FieldTypeImage strange white outline on transparent png's

[bbeer]

Hi
I have a very strange error in one of my installation. Transparent png's are being added a white outline on resized images.
We crop the image with width only like
 

$image = $image ? $image->width(400)->url : '';

I am a bid lost here. Anyone having the same issue?

PW 1.0.174
PHP 7.4

Your help is much appreciated!

[horst]

image example? (original AND issue variation)

[bbeer]

Hi Horst

here the images. Left original, left cropped

[horst]

Yep. I bet that this are 99.9% transparent pixels from the originals cutout pictures. I mean the originals were photographed on a more or less white background, then it get cropped not by a hard pixel path but by some tool that uses cropping by transparency mask. After that, a shadow drop was added. In the original images the cropped out area is visually not seen, but there are some pixels with a special setting: color white & transparency 100%. It would have been better, if the cutout had be done by hard cropping, 1-2px into the object.

If this currently is resized by GD-lib (PWs default or fallback engine), you may try to switch to ImageMagick engine if the server allows this.

 

[bbeer]

it must be something like this. we have not had this problem before. The thing is that the server is already set to imagick. So I guess there is no other way but to fix the images accordingly.

Thanks a lot!

[horst]

2 hours ago, bbeer said:

it must be something like this. we have not had this problem before. The thing is that the server is already set to imagick. So I guess there is no other way but to fix the images accordingly.

Thanks a lot!

One last try: You may try to (re)save an original image in Photoshop as 24bit PNG with transparency, just to make sure it definetly get handled by the imagick engine. (There is a small chance that, for example, 8bit PMGs with transparency (or different types of transparency) get not handled by imagick, also if you selected it as first engine. PW does an image inspection and if the current prefered engine is marked not to be able to handle that format combination correct, it will be passed to the next engine in the chain. 24bit PNG with transparency definetly will be handled by imagick. (The last one in the chain always is GD, as fallback).