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vBulletin decreases the quality of images when resizing

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  • Wayne Luke
    replied
    The base quality of the resized image (always a JPEG) is set to 75% in a number of places throughout includes/image.php. These would have to be changed to 100 since jpeg is a lossy format.

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  • Zachery
    replied
    if the quaility is going down, something is being done.

    An image must pass all 3 limitations to not be changed, filesize, height, and width. If it goes over any one of those it gets resized.

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  • yogesh
    replied
    Has anyone had any success with this? Even if I upload images which do not have to be resized i.e. are well withing the dimension and file size limit, still the image quality goes down a little, even though file size doesn't!

    Tried to set all quality options to 100 in class_image and sharpening to false, still no headway.

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  • Andy
    replied
    Originally posted by valerios View Post
    I do not understand...
    Sharpen it isn't the contrary of blur?

    So if i put sharpen = false is the same to say Blur = true !!

    Am I missing something?
    If an image looks sharp to begin with, sharpening it will make it look pixalated.

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  • valerios
    replied
    Originally posted by Andy View Post
    I assume you are not using thumbnails and when vBulletin resizes a very large image (for example a 2500px width image) to a smaller image (for example a 1200px width image) you are noticing an image quality loss. You can do these two things to make the image resize look perfect.

    1) Use Imagemagick.
    2) Hack the following php file

    /includes/class_image.php

    Remove the sharpen effect on attached images, change true to false.

    Line 750

    function fetch_converted_image($filename, $output, $imageinfo, $thumbnail = true, $sharpen = true)
    I do not understand...
    Sharpen it isn't the contrary of blur?

    So if i put sharpen = false is the same to say Blur = true !!

    Am I missing something?

    Leave a comment:


  • Andy
    replied
    Originally posted by rughis View Post
    could cause any side effects to existing attachments?
    Zero.

    Leave a comment:


  • rughis
    replied
    Switching to imagemagick (if the host supports it) could cause any side effects to existing attachments?

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  • Andy
    replied
    I assume you are not using thumbnails and when vBulletin resizes a very large image (for example a 2500px width image) to a smaller image (for example a 1200px width image) you are noticing an image quality loss. You can do these two things to make the image resize look perfect.

    1) Use Imagemagick.
    2) Hack the following php file

    /includes/class_image.php

    Remove the sharpen effect on attached images, change true to false.

    Line 750

    function fetch_converted_image($filename, $output, $imageinfo, $thumbnail = true, $sharpen = true)

    Leave a comment:


  • kh99
    replied
    I think the Thumbnail Quality option is used when resizing, even if it's not a thumbnail, so you might try increasing that (although that will obviously decrease the dimensions of the image to stay within the same file size). It will also increase the file size of thumbnails.

    Leave a comment:


  • Zachery
    replied
    Well if the image goes over the size, height, or width limits it has to be resized. There is no way to keep the same quaility when re-sizing an image.

    If you want the original to be stored in the original size you need to make sure those attachment limitations are in place to allow images to be uploaded without being re-sized.

    ImageMagick as a whole is better.

    Leave a comment:


  • rughis
    replied
    I have the same "problem".

    I'm using GD image processing library. ImageMagick is another option, but I don't know if the quality in image resizing is better

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  • pokusek
    replied
    I mean uploaded pictures from user's PC. I did not check the quality of images uploaded from another server.

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  • rughis
    replied
    Do you intend attached images or external images linked to the forum?
    Last edited by rughis; Sat 21st Jan '12, 10:33am.

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  • pokusek
    started a topic [Forum] vBulletin decreases the quality of images when resizing

    vBulletin decreases the quality of images when resizing

    Resized photos look blurry. Is there a way to avoid that?

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