2004.01.21 09:15 "[Tiff] change fax resolution", by Takahashi Ryo

2004.01.22 02:04 "Re: [Tiff] change fax resolution", by Takahashi Ryo

Hello. Thank you for the previous replies.

I have a program using libtiff that converts a monochrome PNG of 1728x2280 pixels to a Group3 tiff fax with 200x200dpi. Now, starting from the previous PNG file, I would like create a tiff of 200x100dpi. Using the same PNG image but setting the output tiff resolution to 200x100dpi the aspect ratio changes and image looks streched (I suppose that's normal).

My first guess was that it was something related with libtiff, but based on the previous replies, I guess the correct way of do that would be:

  1. Create the PNG image of 1728x2280
  2. Reduce the height to 50%, so I get a PNG image of 1728x1140 using something like ImageMagick
  3. Save the tiff image with the TIFFTAG_YRESOLUTION set to 100

Is this the correct way of do it?

Thank you.
Best regards,