wwp@yahoogroups.com:
Re: file size and a significant loss of resolution
Markus Altendorff 2006-Jul-01 22:48:00
Caroling Geary wrote:
>
>
> On Jul 1, 2006, at 6:19 AM, Markus Altendorff wrote:
> >
> > 4) Save as "raw/uncorrected master file" (JPEG, maximum
> > quality - for the archive)
> I save as TIFF
Well, i'm using JPEG mainly for reasons of file size. The
JPEG at maximum quality reliably reduces the size by about
1:5 or 1:6, and the maximum difference in loss was less than
1% (or, in then 8-bit scale of 0-255, it's within +/-2 or 3
units) of the original color values - i'm willing to live
with that if it means i don't need a whole CD-Rom for each
single picture ;)
Also, i'm not saving to JPEG, then opening it, then scale
etc. - i'm preparing the image (uncompressed) and save the
various sizes to JPEG "all at once", i.e. retaining the
uncompressed image in Photoshop's RAM :)
> > 6) Sharpen excessively :) - most of the time, 300 % strength
> > and 0.5 (rarely up to 1) pixels radius.
> Wow, I've never sharpened over 200%. Must try. Assuming you are using
> Photoshop|Filter| Sharpen|Unsharp Mask ..., what Threshold value do
> you use then?
I try not to use the threshold, i.e. zero. I'm used to
preparing images for print, and the artificial "grain" the
sharpen filter may add is acceptable if it's evenly
distributed across the whole picture. Also, with the rather
high resolutions the "grain" disappears when scaling down,
but the perceived sharpness remains.
> I never sharpen the master. I only sharpen the final source file for
> any one target pano size. For WWP, one for the full screen. Then back
> to the master to save a smaller image size for the regular pano. I
> think if you sharpen the master and then resharpen the source, you
> are sharpening the sharpens and getting JPEG artifacts, increasing
> file size.
That's true - though the intensity of JPEG artefacts usually
is not that bad as most people seem to believe. That's the
reason i'm saving one "non-treated" version as well, in case
i need to start over. I'm "double-sharpening" most of the
time - 1) the highres source, 2) the
"scaled-to-delivery-size" version (mainly because at scaling
down to 33%, most of the sharpness of 1) is lost in the
bicubic interpolator...
> >
> > I'm not adding a low-res preview. ... also, i'm an occasional ST-
> > TNG watcher [holodeck,
> > anyone? ;) ]
> >
> Star Trek-The Next Generation watcher, I get. Do you mean you like
> the grid effect as relating to the holodeck?
Exactly :) - i was wondering why Apple always had this grid
in the background of VR files...?
> At first I thought you
> meant there was some online environment or game, where you could use
> your own pano as background. I thought you meant that a preview track
> would not work for that. I went searching, but didn't find any such
> venue. It's a cool idea. I provide the setting and the program
> provides the characters.
That was/is actually how most of 3D games create their "far
background" (not a technical term...), since textured cubes
are something that's not taxing on modern graphics cards.
> Otherwise, I like your workflow description, thanks, and will ponder
> file and image sizes some more.
Glad to be of help :)
-Markus