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January 2004

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2004.01.21 09:15 "change fax resolution", by Takahashi Ryo
2004.01.21 12:15 "Re: change fax resolution", by Andrey Kiselev
2004.01.22 02:04 "Re: change fax resolution", by Takahashi Ryo
2004.01.22 02:13 "Re: change fax resolution", by Joris Van Damme
2004.01.22 07:39 "Re: change fax resolution", by Andrey Kiselev
2004.01.22 09:20 "Re: change fax resolution", by Joris Van Damme
2004.01.22 11:50 "Re: change fax resolution", by Joris Van Damme
2004.01.27 08:48 "Re: change fax resolution", by Takahashi Ryo

2004.01.22 02:04 "Re: 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,

Ryo.