[OS X TeX] PDF resolution redux

[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.

BB


____________________________________________________
_________________________________ Bernhard Barkow __
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__ mail bb at creativeeyes.at __ www.creativeeyes.at __
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