On 28 Jun 1999 17:08:09 -0400, par### [at] fwicom (Ron Parker) wrote:

>On Mon, 28 Jun 1999 15:40:10 -0400, TonyB wrote:
>>This is extremely cool. This MUST be included into POV-Ray 3.5 or 4.0
>>(or at least the SuperPatch). =)
>
>I'm generally opposed to JPEG output, because it's lossy.  Imagine
>if you just finished a 3-day render only to discover that the
>quality level on the output wasn't sufficient.  Who would you
>blame, yourself or the guy who chose the default quality level?

Anyone who used JPEG output for an important 3-day final render should
re-examine their motives for doing so. I wouldn't use JPEG output for
a situation like this. Anything that I devote 3 days of machine time
to, will be something that I place a high value on. Anything that I
place a high value on would usually be rendered in PNG, unless there
is some good reason not to use PNG in that particular case.

>I know *I* don't want that kind of support headache. 

One easy way to cut out almost all of the potential "uninformed user
support headache" is to have POV issue a warning statement something
like this: 

"Warning: This scene is being rendered to the JPEG image format to
reduce the image file size. Some noticeable image degradation might
occur. To avoid noticeable quality loss, either us a higher JPEG
Quality setting, or use an output image format other than JPEG."

> Besides, what does JPEG gain you that you can't get with PNG?


(1)
Smaller-than-PNG file sizes.  In many cases, MUCH smaller file sizes
can be attained using JPEG, instead of PNG. The smaller file size has
many possible advantages and potential applications.

This can be most helpful to someone with a large collection of
raytraced images. For critical archival storage of works with possible
commercial or historic value, PNG would be the better option. To be
realistic about the matter, most of us have several images which don't
fall into that category. I dare to say that most of us could place ALL
of our personal creations in the "non-critical" category, if our egos
would allow us to be honest about the issue.

I personally create a LOT of images that I consider "tests". Maybe I'm
refining a scene I'm working on, and would like to keep copies of the
different versions of the image I create during the creative process.
Sometimes I like to create reference images of objects or textures for
future reference. Many of my final scenes are not rendered in a
resolution adequate for quality printing to paper or film. They are
only fit for viewing on a computer screen. If I kept all these images
in PNG format, I would run out of hard disk space much faster. I seem
to always be running out of disk space as it is. Keeping everything in
PNG format would only make matters worse.

I personally reserve PNG for my favorite final renderings. All my
other pov images are archived in JPEG.


(2)
Much broader compatibility with other graphics programs. I know
several people who don't have graphics software that will open a PNG
file, but they do have graphics software that opens JPEG files. JPEG
is the most widely supported compressed image format.

(3)
JPEG is the preferred format of most people for webpage usage (for
photo realistic images.) If rendering images for the web, most people
will want to use JPEG instead of PNG. Even IRTC entries are
distributed in JPEG format. The vast majority of images on the
new.povray.org server are in JPEG format. People chatting on IRC who
want to share their latest POV-Ray creations with their friends will
usually transmit the file in JPEG format. Why not have the *option* of
rendering some of these images directly and not have to create them
with a separate image conversion program?



>On the other hand, using JPEG images as imagemaps, bumpmaps,
>and so on is a pretty good idea.

We certainly agree on this.

********************************************************************

Lastly, I want to say that all the opponents of JPEG output are acting
as if it were a proposed *replacement* for one of their favorite
image formats currently supported. Nothing is further from the truth.
JPEG output would be an *option* available to those users who desired
to use it. No one will make anyone render in JPEG. And quite frankly,
why should anyone care what format *someone else* renders their file
in? If it isn't your file, why on earth would you care? It will never
be the default output format. If someone uses it, it will be because
they *wanted* to do so. Who are we to tell them they shouldn't?

Later,
Glen Berry

IMP Vice Coordinator, and Communications Director
IMP Website: www.imp.org
My Website:  www.ezwv.com/~mclilith/index.html

Email:  7no### [at] ezwvcom
(remove the "7" to reply via personal email)

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