Re: dashed lines with GD [ was Re: symbol/color/line consistency in terminals]

[m s. <mw...@us...>]

> ----- Original Message -----
> From: "Ethan A Merritt" <merritt@u.washington.edu>
> To: gnu...@li...
> Subject: Re: dashed lines with GD [ was Re: symbol/color/line consistency=
 in	terminals]
> Date: Sun, 11 Feb 2007 21:44:45 -0800
>=20
>=20
> On Sunday 11 February 2007 21:25, Daniel J Sebald wrote:
> >
> > > However, it would be nice to set DPI somehow through GD.  > It=20
> > would simplify things when I import images into Word or=20
> > PowerPoint. Well, that isn't too difficult, is it?
>=20
> Actually, it is.
>=20
> The PNG standard does not provide a place to store dpi.
> Some apps store it in a comment record, but that is idiosynchratic,
> and anyhow gd does not (yet) support comment records in PNG.
>=20

OK so it not DPI but its close.

The PNG specification supports a chunk called pHYs which related pixels to =
phyiscal dimensions.

LIBPNG has the following:
    png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
        unit_type);
    res_x       - pixels/unit physical resolution
                  in x direction
    res_y       - pixels/unit physical resolution
                  in y direction
    unit_type   - PNG_RESOLUTION_UNKNOWN,
                  PNG_RESOLUTION_METER

So it would appear the GDLIB could would need to a way to call png_set_pHYs=
.  Then modify gd.trm to accept a resolution setting.

Mike Sutton

p.s.  As a temporary workaround I run ImageMagick's convert with the -densi=
ty option to set resolution.


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