Sietse, I have confirmed, after significant testing, that 'convert -density 72' against existing non-png images produces the expected results in context output pdf documents. But I'm left with another problem, again something that becomes apparent as the difference between having two output formats in my document workflow: markdown -> pandoc -> html/text -> context tex -> pdf. This time it's images that are too wide for the available textarea in the pdf document. Now that the dpi is set, they display at the expected full resolution, yet if they are greater than 6.5*72=438 pixels, they go over the right margin. I know I can, individually, modify each /externalfigure directive and add 'width=\textwidth', but that really is a PITA. This document will have close to a hundred images. I will investigate using a commandline script, exif data, and convert to work through all of the images in the folder to scale/resize them so that they fit in the PDF document margin width. I don't think that the html version will suffer if I do this. So, again, thanks for your help! Best regards, Guy S. On 11/21/2012 02:36 PM, Sietse Brouwer wrote:

Guy wrote:

...

Well, that lead to an interesting experiment. I used convert to -resample a set of images to 300dpi and redid the compile. They are all now too bod, many off the right side of the page. Then did the same but set to 72. They are still too big. Odd, from too small to too big. I think you don't want -resample, but -density:

# density given in dpi convert pic.jpg -density 72 pic-out.jpg

convert -density keeps the pixel size and changes the display size by setting the density metadata. convert -resample keeps the display size and changes the pixel size by resampling at a certain density. (This explains why the picture remained the same too-large size when you resampled at 72 and 300 dpi.)

Because you want to change the display size (and also because resampling is a lossy process), I think you want -density.

As for the density value you want to use: Your picture is 547px wide, so if you want it to display it 3 inches wide you should set its density metadata to 547/3 = 183 dpi.

Does this work? All the best, Sietse

-- "There is only love, and then oblivion. Love is all we have to set against hatred." (paraphrased) Ian McEwan Guy Stalnaker, I^2@DOIT, 1210 West Dayton Street, Room 3209 CSS, Madison WI 53719-1220, jstalnak@wisc.edu, work 608.263.8035, cell 608.235.4718, fax 608.265.6681, page page-guy@watchdog.doit.wisc.edu

In case anyone else has been following this thread, here is the shell script I wrote to resize an image width to 6.5x72dpi so they fit in the standard letter pagesize \textwidth with 1-inch margins and add image density/resolution information so that context correctly sizes them in the PDF output file. <code> #!/bin/bash #set -x TEXTWIDTH="438" #6.5inches x 72 dpi for i in *.jpg ; do SIZEX="$(exiftool -imagewidth $i | awk '{print $4}')" SIZEY="$(exiftool -imageheight $i | awk '{print $4}')" echo "Image $i is $SIZEX x $SIZEY, max X is $TEXTWIDTH ..." if [[ $SIZEX > $TEXTWIDTH ]] ; then convert $i -resize $TEXTWIDTH -density 72 $i echo "resized image $i from $SIZEX to $TEXTWIDTH." fi done </code> Regards, Guy On 11/21/2012 02:36 PM, Sietse Brouwer wrote:

Guy wrote:

...

Well, that lead to an interesting experiment. I used convert to -resample a set of images to 300dpi and redid the compile. They are all now too bod, many off the right side of the page. Then did the same but set to 72. They are still too big. Odd, from too small to too big. I think you don't want -resample, but -density:

# density given in dpi convert pic.jpg -density 72 pic-out.jpg

convert -density keeps the pixel size and changes the display size by setting the density metadata. convert -resample keeps the display size and changes the pixel size by resampling at a certain density. (This explains why the picture remained the same too-large size when you resampled at 72 and 300 dpi.)

Because you want to change the display size (and also because resampling is a lossy process), I think you want -density.

As for the density value you want to use: Your picture is 547px wide, so if you want it to display it 3 inches wide you should set its density metadata to 547/3 = 183 dpi.

Does this work? All the best, Sietse

-- "There is only love, and then oblivion. Love is all we have to set against hatred." (paraphrased) Ian McEwan Guy Stalnaker, I^2@DOIT, 1210 West Dayton Street, Room 3209 CSS, Madison WI 53719-1220, jstalnak@wisc.edu, work 608.263.8035, cell 608.235.4718, fax 608.265.6681, page page-guy@watchdog.doit.wisc.edu