Thumbnail creation: no white background for GIFs

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12 years 1 month ago #29425 by Rooney
Hi, I don't know if this is a bug, but I have many logos on our page just to show who our clients are. If I am using a PNG file the white background stays white for the thumbnails. If I am using GIF files the background becomes greyish even if the thumb quality is set to 100% and the file dimensions do not change.

Rooney

Joomla! 3.9.24 and FC 3.3.9

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12 years 1 month ago #29426 by ggppdk
Is there some phpthumb parameter we can apply ?


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12 years 1 month ago #29510 by kenmcd
.
The Quality setting only affects JPGs.
No effect on PNGs or GIFs.

If your original image has any transparency such as a transparent PNG, depending on exactly how that is created will affect how that converts in a GIF (which only allows one color to transparent).

GIFs will always have some odd color conversions going from a full color JPG or PNG to the limited palette in the GIF.

And it also appears phpThumb uses dithering by default in GIFs and that can cause some odd color selections in the conversion.

Post a link to the original file if you would like to troubleshoot more.
.

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12 years 1 month ago #29512 by Rooney
Hi,

here are the files that have been uploaded with Flexicontent: www.muenstermann.com/uebersicht/referenzen.html

The original files are here: www.muenstermann.com/en/references.html

As you can seethe original files are simple gifs. PNGs by the way are not effected. I started to use pngs here and white is not changed into greyish: www.muenstermann.com/anwendungsb ... ehmen.html

Rooney

Joomla! 3.9.24 and FC 3.3.9

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12 years 1 month ago #29514 by ggppdk
thanks for the information Ken, i did not think/know of the dithering issue (i know what is dithering, just did not think that this could be the reason)

i took a quick look at this (this link has the parameters for running phpthumb)
phpthumb.sourceforge.net/demo/do ... readme.txt

we could add this option for gifs:
&fltr[]=rcd|256|0

this will run phpthumb with 256 colors and zero dithering

can you test on your site?


-- Flexicontent is Free but involves a big effort on our part.
Like the our support? (for a bug-free FC, despite having a long list of functions) Like the features? Like the ongoing development and future commitment to FLEXIcontent?
-- Add your voice to the FLEXIcontent JED listing with a 5-star...

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12 years 1 month ago #29522 by Rooney

ggppdk wrote: can you test on your site?


Of course. What shall I do?

Rooney

Joomla! 3.9.24 and FC 3.3.9

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