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Re: Creating JPEG files [message #32423]

Wed, 09 October 2002 09:30

Med Bennett
Messages: 109
Registered: April 1997

Senior Member

Med Bennett wrote:

> Mike Jewison wrote:
>
>> I have a short program which generates a 2D plot using a standard call
>> to the PLOT procedure, displaying to the X-windows device. I would
>> like to also have this plot dumped to a JPEG file for display on a web
>> page. Although the plot looks just fine on the screen, when I issue
>> the following command:
>>
>> WRITE_JPEG, JPEG_File, TVRD()
>>
>> the resultant JPEG file has very little contrast (i.e. it's basically
>> near-black on black). I know the WRITE_JPEG procedure is better
>> suited to images rather than plots, but is there (a) a better way to
>> create a JPEG file of a plot rather than what I'm doing, or (b)
>> another file format which IDL supports that would do a good job of
>> creating a web-compatible image format? I used to use the WRITE_GIF
>> format until IDL dropped support for it.
>>
>> Many thanks.
>>
>> - Mike
>
> JPEG is really better suited for continuous tone graphics, i.e. photos,
> shaded surface plots, etc. If you're trying to capture line art, ie. a
> plot with only a few distinct colors, I believe it would be better to use
> a GIF or PNG file format. The lossy JPEG compression does ugly things to
> line graphics, and actually can create larger files than one of the
> lossless graphics formats.

Sorry, I didn't read your whole post before making my response. I believe
PNG is what you should try.

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[Message index]

		Re: Creating JPEG files By: Med Bennett on Wed, 09 October 2002 09:30
		Re: Creating JPEG files By: Med Bennett on Wed, 09 October 2002 09:26
		Re: Creating JPEG files By: David Fanning on Wed, 09 October 2002 08:30
		Re: Creating JPEG files By: David Fanning on Wed, 09 October 2002 08:19
		Re: Creating JPEG files By: R.Bauer on Wed, 09 October 2002 08:09
		Re: Creating JPEG files By: David Fanning on Wed, 09 October 2002 08:12

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