On Thu, 5 Jan 2017 23:47:00 -0500
Cesar Romani
The quality of the rotated pdfs, which are images, drops off a little. For example, some characters are not so sharp as in the original pdf.
If I use GraphicsMagick I would remedy this with the parameter -density as in: gm convert -density 300x300 original.pdf -rotate 45 rotated.pdf
From the web: "A PDF file does not have a density anyway. IM will apply a default interpretation of 72dpi unless you override it (e.g. -density 300x300 -units pixelsperinch)." Testing: convert original.tif -rotate 45 rotated.png keeps the original density. 1) original.tif was 6000x6000; rotated.png is 8488x8488 (2400dpi) 2) converting to rotated.tif fails convert: TIFF: negative image positions unsupported rotated.tif @ error/tiff.c/WriteTIFFImage/3609. 3) converting to rotated.pdf does produce a much reduced resolution image. Indeed, PDF is container, not the best format for manipulating bitmap images. I take two approaches to this: 1) I manipulate/modify the images explicitly "upstream" before including them in ConTeXt, using any of my favorite tools; or 2) I manipulate/modify the images using MetaPost, within ConTeXt. This gives very satisfactory results and does not rely on ImageMagik. Alan