[MF3D.FORUM:504] Re: stereo cards on the web

[Marco Pauck <pauck@xxxxxxxxxxxx>]

Tom Deering wrote:
[...]
> I have a couple of comments about web images.  First of all, the
> David's photos are *stunning*.  The cards are very neatly made,
> really a treasure to look at.
> 
> Howver, there are a couple of ways the clarity could be increased
> while minimizing the download time.  The JPEG artifacts are very
> heavy, almost ruining the image for stereo purposes, which is a
> shame.
[...]

I agree with Tom's remarks and suggestions except one:

> Then, either I would save the images as much higher quality JPEGS, or
> I would save them as greyscale GIFS, maybe 64 or 128 color palette.
> Since these are greyscale images, the best method would be a
> judgement call.  Either method would increase the file size, but if
> the file size was smaller to begin with, the increase might be small.

Never cripple high quality b/w prints by quantizing them to less
than 8 bits (i.e. 256 grey values)!

There are usually two points where this may occur:
1. by using an inappropriate image format or color palette
2. by using sub-optimal scanning parameters

The second point is illustrated by some of the images (for example
"Devil's Tower") that suffer from an unnecesarily limited range of
grays.

This leads to an additional suggestion from me:
Learn to use the histogram and gamma control features of your
scanning program. These features (as well as 'unsharp masking')
are the most important controls that affect image quality when
scanning prints and especially negatives or slides.

And they are powerful!
A traditional fine art printer uses similar controls by selecting
an appropriate gradation of the paper, possibly split-grading
highlights and shadows, or by using a two-bath development process,
nearly in all cases by 'dodging' and 'burning' and maybe by using
some even more esoteric techniques. This is unbelievable time-consuming!
With Photoshop & Co. you can get at least the same degree of control
with only a few mouse clicks!

> This is not meant as a criticism of the person who did all the
> scanning and web page work, which is a big job.  There are a lot of
> images there.  I'm just pointing out that another scheme might be
> better in the future.
[...]
> And as I said, the images themselves are very nice.  Congratulations, David!

I can only second that, and please keep them on the Web!

	Marco
--
Marco Pauck -- marco@xxxxxxxx -- http://www.pauck.de/marco/
For every complex problem, there is a solution that is simple,
neat, and wrong.  -- H. L. Mencken