POV-Ray : Newsgroups : povray.newusers : JPG output Server Time
28 Nov 2024 17:43:56 EST (-0500)
  JPG output (Message 1 to 6 of 6)  
From: Tommy P  Thompson
Subject: JPG output
Date: 23 Dec 1999 14:18:19
Message: <38627566.74412FCF@sprintmail.com>
With Povray, is it possible to output JPG or GIF files? I know there are
command line options for .bmp, .ppm, and .tga files but no jpg or gif.
If povray cant do this, then what steps should I take to convert to JPG
format?. All the povray scenes I see on the net are in JPG format.


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From: Phil Clute
Subject: Re: JPG output
Date: 23 Dec 1999 14:35:30
Message: <38627980.C1B5C5E1@tiac.net>
There's a cool little program I use called IrfanView
http://stud1.tuwien.ac.at/~e9227474/english.htm
This will view and convert several file types including
.jpg .
For other options you may want to check out the links section at
http://www.povray.org/ --> 3D programs --> conversion utilities.
-- 
Phil
...coffee?...yes please! extra sugar,extra cream...Thank you.


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From: J  Grimbert
Subject: Re: JPG output
Date: 24 Dec 1999 02:54:39
Message: <386326C6.6A53A010@atos-group.com>
"Tommy P. Thompson" wrote:
> 
> With Povray, is it possible to output JPG or GIF files? I know there are
> command line options for .bmp, .ppm, and .tga files but no jpg or gif.
> If povray cant do this, then what steps should I take to convert to JPG
> format?. All the povray scenes I see on the net are in JPG format.

I would say that you do not want to raytrace a picture and have the 
original result in JPG or GIF. 

Why ?

GIF: limited to 256 colours, and some americans would have a legal problem
  with a silly patent on compression.

JPG: the compression algorithm is with loss. Moreover the compression need
a spatial transformation of the picture, which imply you will only have the
file at the very end of the rendering (no Continue)

If you want a modern image format, go for PNG (and its already in POV).
It's lossless, 24 (or even 48 bits), can have alpha information like gif
and has no legal issue!


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From: Nieminen Juha
Subject: Re: JPG output
Date: 27 Dec 1999 05:35:54
Message: <3867410a@news.povray.org>
J. Grimbert <jgr### [at] atos-groupcom> wrote:
: JPG: the compression algorithm is with loss. Moreover the compression need
: a spatial transformation of the picture, which imply you will only have the
: file at the very end of the rendering (no Continue)

  Nope, you don't need the whole picture before being able to start the
conversion.
  When converting to the JPEG format, the original image is splitted into
square blocks (I don't remember how many pixels, but perhaps 8x8 or 16x16).
Then a fourier-transform is applied to each one of these blocks (with several
filterings which I don't know of) and finally (AFAIK) the result is compressed
into the final file. (Please correct my mistakes if I made any).
  This means that you need as many lines of the original image as the block
size at a time to be able to start compressing (ie. 8 or 16 lines).

: If you want a modern image format, go for PNG (and its already in POV).
: It's lossless, 24 (or even 48 bits), can have alpha information like gif
: and has no legal issue!

  Actually the GIF format does not support alpha channel. It supports marking
one of the colors as being transparent. This is not the same as an alpha
channel (ie. for each pixel you can say how transparent it is). PNG supports
it.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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From: Ian Burgmyer
Subject: Re: JPG output
Date: 30 Dec 1999 02:08:47
Message: <386b04ff@news.povray.org>
J. Grimbert <jgr### [at] atos-groupcom> wrote in message
news:386326C6.6A53A010@atos-group.com...
> I would say that you do not want to raytrace a picture and have the
> original result in JPG or GIF.
>
> Why ?
>
> GIF: limited to 256 colours, and some americans would have a legal problem
>   with a silly patent on compression.

Beyond simply silly.

> JPG: the compression algorithm is with loss. Moreover the compression need
> a spatial transformation of the picture, which imply you will only have
the
> file at the very end of the rendering (no Continue)

This is very good to post on a messageboard because of it's small size and
portability.  Virtually every graphical newsclient can use JPG without a
problem.

It's not good for the original, because as you said, it's lossy and you
can't interrupt an image and expect a result, sadly.

> If you want a modern image format, go for PNG (and its already in POV).
> It's lossless, 24 (or even 48 bits), can have alpha information like gif
> and has no legal issue!

However, it's not fully supported by everything (not by anything if you want
full, 100% support), it's quite a bit larger then JPG, from my experience,
but it is a very good format, and I'm hoping that it'll become the standard.

Also, I think a few games use PNG to store textures.

--
This message brought to you by:
-=< Ian (the### [at] hotmailcom >=-

Please visit my site at http://spectere2000.cjb.net! :)


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From: Matt Giwer
Subject: Re: JPG output
Date: 30 Dec 1999 03:07:54
Message: <386B3CFE.CDF5EF77@ij.net>
"Tommy P. Thompson" wrote:

> With Povray, is it possible to output JPG or GIF files? I know there are
> command line options for .bmp, .ppm, and .tga files but no jpg or gif.
> If povray cant do this, then what steps should I take to convert to JPG
> format?. All the povray scenes I see on the net are in JPG format.

    Way back when, real programmers coded in Hex directly to ZIP
distribution format.

    The problem here is similar. While theoretically possible, it would take
a hell of a lot of practice. Both of those are compressed formats. As such
they work on clusters of pixels, horizontal and vertical. POV renders
horizontal lines.

    Now POV could render in small squares but compression routines would
have to know what is in the adjacent squares for storing what is near the
boundaries.

    So ultimately, POV would have to do exactly what it does now and then
convert to GIF or JPEG. And since there are plenty of free conversion
utilities, why not let the user do it himself? And with JPEG there is the
user option of quality as a variable but it does not really mean anything
quantifiable despite the percents and slide bars you might see on the
conversion utilities. They are purely qualitative.


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