[OS X TeX] PDF resolution redux

Armin Goralczyk agoralczyk at gmail.com
Thu Aug 11 19:41:07 CEST 2005

Am 11.08.2005 um 09:24 schrieb Bernhard Barkow:

> On 10.08.2005, at 20:59, Armin Goralczyk wrote:
>>>> Thanks. I just realized that my question wasn't put well. What I  
>>>> want is to tell Pdf(la)tex to scale down the document. Of  
>>>> course, I could downsample the individual images, but I'm  
>>>> looking for a solution which would allow to keep one version of  
>>>> the original images and have different pdfs created depending on  
>>>> the resolution I need on a specific occasion. Let's say a low  
>>>> resolution to put the document on the web and a high resolution  
>>>> for printing. So I don't want to manipulate the images but have  
>>>> pdftex downsample them.
>>> Look up \pdfimageresolution in the pdftex manual.
>> I tried to use '\pdfimageresolution 30' in the preamble but size  
>> of document did not change. Do I have to apply it to every image?  
>> Also from pdftex manual:
>> \pdfimageresolution (integer)
>> The integer \pdfimageresolution parameter (unit: dots per inch,  
>> dpi) is a last resort value, used only for bitmap (jpeg,
>> png) images, but not for pdfs. The priorities are as follows:  
>> Often one image dimension (width or height) is stated
>> explicitely in the TEX file. Then the image is properly scaled so  
>> that the aspect ratio is kept. If both image dimensions are
>> given, the image will be stretched accordingly, whereby the aspect  
>> ratio might get distorted. Only if no image dimension
>> is given in the TEX file, the image size will be calculated from  
>> its width and height in pixels, using the x and y resolution
>> values normally contained in the image file. If one of these  
>> resolution values is missing or weird (either < 0 or > 65535),
>> the \pdfimageresolution value will be used for both x and y  
>> resolution, when calculating the image size. And if the
>> \pdfimageresolution is zero, finally a default resolution of 72  
>> dpi would be taken. The \pdfimageresolution is
>> read when pdfTEX creates an image via \pdfximage. The given value  
>> is clipped to the range 0..65535 [dpi].
>> Doesn't this imply use of \pdfimageresolution just in the case if  
>> a value for either width or height is missing? I am a novice so I  
>> may be wrong, but for me it is not working. What is wrong? Thanks  
>> for help.
> Did you try
> \pdfimageresolution=300
> for 300dpi images (that's what the man page states)?
> However, the documentation sounds as if there would be no  
> resampling at all, but the resolution parameter is only used to  
> calculate the image size when there is no resolution specified in  
> the image file (i.e., the number of pixels won't be reduced, but  
> distributed over an appropriate area, to put it simple...).
> Thus it seems to me that the only way to accomplish the original  
> task (ensuring that images in the finished pdf document are not  
> beyond a maximum resolution (dpi))  is to use either Acrobat or a  
> Quartz filter on the whole pdf document, as described in earlier  
> postings.

No i tried 72 dpi and less because 72 dpi is default value (see  
manual as above). Quartz filter worked for me, I just wanted to know  
if \pdfimageresolution works.
Thanks for help.


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