[pdftex] graphic{s,x} PNG + pdflatex bug

[Jim Diamond]

On Fri, May  7, 2010 at 13:25 (+0100), Thanh Han The wrote:

> On 5/7/10, Jim Diamond <Jim.Diamond at acadiau.ca> wrote:
>> On Fri, May  7, 2010 at 08:19 (-0300), George N. White III wrote:

>>> On Thu, May 6, 2010 at 3:55 PM, Jim Diamond <Jim.Diamond at acadiau.ca> wrote:

>>>> On Thu, May  6, 2010 at 15:36 (-0300), George N. White III wrote:

>>>>> On Thu, May 6, 2010 at 2:33 PM, Taco Hoekwater <taco at elvenkind.com> wrote:
>>>>>> Nico Schlömer wrote:

>>>>>>> Hi all,

>>>>>>> I experienced a weird bug using \includegraphics of the graphicx
>>>>>>> package with pdflatex 1.40.10.

>>>>>>> I try to load the attached PNG file, and unlike with other PNG files,
>>>>>>> pdflatex would just bail out with

>>>>>>> ==================== *snip* ====================
>>>>>>> [...]
>>>>>>> [Loading MPS to PDF converter (version 2006.09.02).]
>>>>>>> )
>>>>>>> ! Dimension too large.
>>>>>>> <argument> \wd \@tempboxa
>>>>>>> l.7 \includegraphics{img1.png}
>>>>>>> ?
>>>>>>> ==================== *snap* ====================

>>>>>>> David Carlisle, maintainer of graphicx, suggests that may be a bug in
>>>>>>> pdflatex -- What do you reckon?

>>>>>> Well, this png specifies a resolution of 0.9906 pixel per inch so it
>>>>>> has natural sizes of about 252 inch (6.4m). So in my opinion something
>>>>>> *is* wrong with the png.

>>>>>> Best wishes,
>>>>>> Taco

>>>>> $ identify -verbose img1.png |head
>>>>> Image: img1.png
>>>>> Format: PNG (Portable Network Graphics)
>>>>> Class: DirectClass
>>>>> Geometry: 250x250+0+0
>>>>> Resolution: 0.39x0.39
>>>>> Print size: 641.026x641.026
>>>>> Units: PixelsPerCentimeter

>>>>> I loaded the PNG in Adobe Photoshop and saved it as  img2.png:

>>>>> $ identify -verbose img2.png |head
>>>>> Image: img2.png
>>>>> Format: PNG (Portable Network Graphics)
>>>>> Class: DirectClass
>>>>> Geometry: 250x250+0+0
>>>>> Resolution: 0.39x0.39
>>>>> Print size: 641.026x641.026
>>>>> Units: PixelsPerCentimeter

>>>>> $ pngcheck -vt img1.png
>>>>> File: img1.png (92868 bytes)
>>>>> chunk IHDR at offset 0x0000c, length 13
>>>>>     250 x 250 image, 32-bit RGB+alpha, non-interlaced
>>>>> chunk sBIT at offset 0x00025, length 4
>>>>> red = 8 = 0x08, green = 8 = 0x08, blue = 8 = 0x08, alpha = 8 = 0x08
>>>>> chunk pHYs at offset 0x00035, length 9: 39x39 pixels/meter (1 dpi)
>>>>> chunk IDAT at offset 0x0004a, length 8192
>>>>> zlib: deflated, 32K window, default compression
>>>>> chunk IDAT at offset 0x02056, length 8192
>>>>> chunk IDAT at offset 0x04062, length 8192
>>>>> chunk IDAT at offset 0x0606e, length 8192
>>>>> chunk IDAT at offset 0x0807a, length 8192
>>>>> chunk IDAT at offset 0x0a086, length 8192
>>>>> chunk IDAT at offset 0x0c092, length 8192
>>>>> chunk IDAT at offset 0x0e09e, length 8192
>>>>> chunk IDAT at offset 0x100aa, length 8192
>>>>> chunk IDAT at offset 0x120b6, length 8192
>>>>> chunk IDAT at offset 0x140c2, length 8192
>>>>> chunk IDAT at offset 0x160ce, length 2530
>>>>> chunk IEND at offset 0x16abc, length 0
>>>>> No errors detected in img1.png (16 chunks, 62.9% compression).
>>>>> $ pngcheck -vt img2.png
>>>>> File: img2.png (92076 bytes)
>>>>> chunk IHDR at offset 0x0000c, length 13
>>>>>     250 x 250 image, 32-bit RGB+alpha, non-interlaced
>>>>> chunk bKGD at offset 0x00025, length 6
>>>>> red = 0x00ff, green = 0x00ff, blue = 0x00ff
>>>>> chunk pHYs at offset 0x00037, length 9: 39x39 pixels/meter (1 dpi)
>>>>> chunk vpAg at offset 0x0004c, length 9
>>>>> unknown private, ancillary, safe-to-copy chunk
>>>>> chunk IDAT at offset 0x00061, length 32768
>>>>> zlib: deflated, 32K window, maximum compression
>>>>> chunk IDAT at offset 0x0806d, length 32768
>>>>> chunk IDAT at offset 0x10079, length 26301
>>>>> chunk tEXt at offset 0x16742, length 37, keyword: create-date
>>>>>     2010-05-06T12:39:23-03:00
>>>>> chunk tEXt at offset 0x16773, length 37, keyword: modify-date
>>>>>     2010-05-06T12:35:33-03:00
>>>>> chunk IEND at offset 0x167a4, length 0
>>>>> No errors detected in img2.png (10 chunks, 63.2% compression).

>>>>> Both versions look the same using Imagemagick's display,
>>>>> but img2.png does not give the error, so image size does
>>>>> not explain the error.

>>>> Did you compare the rest of the output of "identify -verbose" ?  There
>>>> may be something illuminating there.  As your pngcheck output shows,
>>>> the photoshop version is quite a bit different.

>>> I did, but it doesn't seem helpful:

>>> $ diff img1.ident img2.ident
>>> 1c1
>>> < Image: img1.png
>>> ---
>>>> Image: img2.png
>>> 310c310
>>> <   Background color: white
>>> ---
>>>> Background color: rgba(0,0,0,1)
>>> 321,322c321,324
>>> <     date:create: 2010-05-06T12:39:23-03:00
>>> <     date:modify: 2010-05-06T12:35:33-03:00
>>> ---
>>>> create-date: 2010-05-06T12:39:23-03:00
>>>> date:create: 2010-05-06T12:50:09-03:00
>>>> date:modify: 2010-05-06T12:50:09-03:00
>>>> modify-date: 2010-05-06T12:35:33-03:00
>>> 327c329
>>> <   Filesize: 92.9KB
>>> ---
>>>> Filesize: 92.1KB

>> Curious.

>> I used "display" and "xv" to create "copies" of the file, and the "xv"
>> one makes pdflatex happy, but the "display" one makes pdflatex crash
>> and burn.

>> xv does change the resolution to 72x72 with "undefined" units, but as
>> George points out, that (by itself anyway) doesn't appear to be te
>> issue.

>> Maybe some pdftex internals person/people will need to chime in,
>> should they feel so inclined.

> Taco is one core member of the pdftex team, and explained it
> all. I don't know what more could be said about this.
> Anyway, here my attempt:

> when a bitmapped image is included, pdftex tries to figure
> out the dimension of the image in the output (let's call
> it the "intended dimension"):

>   (1) if specified explicitly by the user (eg via the keyword
>       "width" or "height"), then use it

>   (2) if not specified explicitly, and the image contains
> resolution, then use it

>   (3) otherwise, use the resolution specified by
>       \pdfimageresolution to calculate the intended dimension.

> [btw, all of this is in the pdftex manual.]

> now let's look at our case:
> ,--------,
>> \includegraphics{img1.png}
> `--------`

> no explicit dimension, but resolution available => step (2)
> taken. Then it turned out that the intended dimension
> (252inch) is too big for (pdf)tex. So the cause of the
> problem (for pdftex) is too big (intended) dimension of the
> image.

Thanh,

thanks for the explanation, but...

George's text above claims that the size is not (by itself) the issue:

>>>>> Both versions look the same using Imagemagick's display,
>>>>> but img2.png does not give the error, so image size does
>>>>> not explain the error.

I would have been happy to accept Taco's comments until reading that.
Would you not agree that Taco's explanation and George's experiment
are contradictory?

Cheers.
				Jim