[pmwiki-users] non-displayed pictures in thumblist2

Petko Yotov 5ko at 5ko.fr
Tue May 25 16:40:47 CDT 2010

On Tuesday 25 May 2010 12:11:17, Peter Bowers wrote :
> On Tue, May 25, 2010 at 10:00 AM, Peter Bowers <pbowers at pobox.com> wrote:
> > I recently installed thumblist2 and populated my upload directory with
> > several pictures.  Everything works very nicely except one picture
> > displays this message, "Parapets1.jpg: 2592x1944, 1186k (May 24, 2010,
> > at 09:39 AM)", instead of the picture.
> Update: I see there is a file left on the server as follows:
>    .th128---ffffff--Parapets1.jpg.jpg.lock
> No other lock files left after processing...
> (Needless to say the thumbnail image is not found in the directory --
> just the full image, and that was created in the same way the rest of
> them were...)
> I've tried deleting and re-uploading the image, but no luck...  This
> image is half the size of some of the largest images in the same
> directory, just FYI (these other, larger images have not had any
> problems)...

It looks like a memory limit problem, and this *is* a big picture. You can see 
the error message when you open the thumbnail url ?action=createthumb, as it 
appears in the html source, directly in the browser. Alternatively, in Firefox 
you can right-click on the text "Parapets1.jpg: 2592x1944..." and from the 
menu select "View image".

The amount of memory needed to process a picture can go as far as 3 times the 
number of pixels: Red, Green, Blue channels (4 times if there is an Alpha 
channel), but usually less is required, depending on the picture complexity I 
believe. This is the memory to open&resize the picture, a little more is 
needed for the full php script. [1]

While the largest monitor sold around where I am has 1920x1200 pixels, most 
people have smaller screens like 1200x900 or even (1024..1366)x768. If you 
really have to use such large pictures, you may try to either allow more 
memory in php.ini, or enable and use ImageMagick.


[1] This is a common limitation to all PHP-GD image processing scripts, 
Thumlblist, Mini, PHPThumb, Qdig... -- if we find a more memory-efficient way 
to create the thumbnails via PHP, we'll change for it. For example, if another 
PHP script running on the same server is able to resize this same picture 
without crashing. :-)

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