perl GD Image resolution problem

[Zhiliang Hu]

I use GD::Image to create figures. Here is an example:
http://sphinx.vet.unimelb.edu.au/QTLdb/tmp/map490151833.png

For publication purposes we need high resolution pictures. I am
seeking expert advice as how can I improve the resolution?

Thanks in advance!

Zhiliang

[xho...@gmail.com]

Zhiliang Hu <zhili...@gmail.com> wrote:
> I use GD::Image to create figures. Here is an example:
> http://sphinx.vet.unimelb.edu.au/QTLdb/tmp/map490151833.png
>
> For publication purposes we need high resolution pictures. I am
> seeking expert advice as how can I improve the resolution?

Hi Zhiliang,

The resolution of a png is one pixel per pixel. You can't get any higher
than that! You should be able to make the entire image larger, for example
by specifying a larger array when you call new on your GD object.
Currently it is 360x402, you could try doubling each.

Or you may need to switch to something other than png, like svg using
GD::SVG.

Xho

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[zentara]

Use a camera with more mega-pixels, and set it to the highest
resolution. ( Usually the largest picture, allowing fewest pictures
in storage).

If you take a low resolution photo, and use a program to make it larger,
each pixel will be duplicated with the same color, to accomodate the
larger size. So the picture will be larger, but the resolution will not
improve.

Resolution comes from the camera's megapixel count and settings.

zentara

--
I'm not really a human, but I play one on earth.
http://zentara.net/japh.html

[Zhiliang Hu]

Many thanks for all your hints. That'll be useful.

--
Zhiliang

[zentara]

On Tue, 6 May 2008 08:29:09 -0700 (PDT), Zhiliang Hu
<zhili...@gmail.com> wrote:

>Many thanks for all your hints. That'll be useful.

I just looked at your sample output, and since it's lines and
text, you could use the Scalable Vector Graphics format, or
.svg

GD has svg output with the module
http://search.cpan.org/~twh/GD-SVG-0.28/SVG.pm

SVG files look like xml, and will change resolution
automatically to adjust to window size.

Google for svg for more info.

[Ben Bullock]

On May 7, 10:22 pm, zentara <zent...@highstream.net> wrote:

> SVG files look like xml

That's because they are XML.

[Zhiliang Hu]

Yes, I do find SVG an interesting tool. I spent some time on it...
ang wonder is there a good tutorial on how to use it? (for example I
made it produce xml like files but not yet viewable on web; Yet to get
fonts to work, etc.)

Many thanks for all who replied with suggestions. These did give me
some insights. Appreciate it.

Zhiliang