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Bug #23497 computation of 35mmFocalLength (exif)
Submitted: 2003-05-05 16:59 UTC Modified: 2005-02-01 22:54 UTC
Votes:1
Avg. Score:3.0 ± 0.0
Reproduced:0 of 0 (0.0%)
From: francois at guillier dot org Assigned:
Status: Wont fix Package: EXIF related
PHP Version: 4CVS-2003-05-05 (stable) OS:
Private report: No CVE-ID: None
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 [2003-05-05 16:59 UTC] francois at guillier dot org 
In the following code (around ligne 3830 of exif.c):

exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "35mmFocalLength" TSRMLS_CC, "%dmm", (int)(ImageInfo.FocalLength/ImageInfo.CCDWidth*35+0.5));

Why is CCDWidth multiplied by 35 knowing than, on 35mm film,
the image actual size is 36x24mm?

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 [2003-05-05 18:16 UTC] helly@php.net 
This is an approximation that maybe is wrong but every manufacturer does its own error. So maybe the correct thing would be to provide an ini setting for that.

If you come up with a hint that shows that 36 is really better i consider changing it. Otherwise there will be now change before next major version.
 
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