Re: Where to obtain JPEG resolution

From: Severian (severian_at_chlamydia-is-not-a-flower.com)
Date: 01/25/05 

Date: Tue, 25 Jan 2005 13:40:52 -0500

On 24 Jan 2005 10:12:30 -0800, "City Dweller" <dc_dweller@hotmail.com>
wrote:

>I use the IJG library to open and process JPEG images.
>
>I am trying to figure out where the image resolution information is
>stored. The fields X_density and Y_density are usually set to 1 and
>density_units to 0, while Windows Explorer reports some of those images
>as 72dpi and others 300dpi. So where is that information stored?
>Neither file has any EXIF tags associated with them, as far as I can
>tell.

If the files were created by Photoshop, there is likely an APP13
marker with Photoshop information, described in the Photoshop
Developer's Kit.

I have no idea why Adobe declined to also update the standard JPEG
density fields. They tend to bastardize every file type they touch. 

--
Sev