Picture size

"Grumpy AuContraire" wrote in message
news


§qu@re Wheels wrote:

On this particular day of this month, in the Year Of The Golden Pig, P &
H Macguire did state:


I am in the process of scanning some old slides of 60s to 90s and
wondered what the optimum size should be for posting on this N/G. They
will be scanned at about 300dpi.

Regards

PJM


Absolutely scan at 300dpi or even more. You can always reduce (dpi, size,
etc.) but no matter what, no matter how a pic is, enlarging more than 25%
is useless and there is much quality degradation.

Avoid 72 dpi like unto the plague. That was a semi-arbitrary resolution
based on the early browsers that could not display more than that, and
the
palettes were also fewer than 256 colours. Those were the old days.
And today's monitors, both LCD and CRT, can display even more than 300
dpi, and do it well.


Please list monitors (any) that display higher resolution than 72 dpi.

My monitor is an Apple Mac 23" (running on a PC) and it has 1920 X 1200.
The vertical dimension is 12" So about 100dpi.

My Sony VAIO notebook has 1920 X 1200 and the screen is 9" high. That's 133
dpi.

There are two issues. Scanning for archive and then the (reduced) size for
posting.

When I scan a slide I do it for archiving and I use 4800. Even that doesn't
do the slide its full credit. For archival, you also need to consider the
colour depth. 48 bit is great for a slide, but normal jpg will only save 32
bit. There is a higher depth jpeg (jpeg2000, I think) but I don't use it.
It's a rare format and I don't trust trust it to supported in 20 years time.

If you do scan a slide at 72 dpi, then you will have an image that is
roughly 72 X 72. Almost unusable.

Regards


snip

On this particular day of this month, in the Year Of The Golden Pig, The
Old Bloke did state:

There is a higher depth jpeg (jpeg2000, I think) but I don't use it.
It's a rare format and I don't trust trust it to supported in 20 years time.

It's not even supported now, AFAIK. Haven't seen one in over a year, and
even then the poster got blasted for using it.

I think PNG will be around for a while; it at least is being used, but
mostly as a hi-res high-colour GIF would be because it has transparency
capabilities.

Filesizes are out of line, though. If they can get that under control, it
might hang around a while.

Meanwhile, the JPEG crowd (Joint Photographic Expert Group) are trying (or
were) to grab royalties as a propriety format. If they ever succeeded,
which is about as likely as me inheriting the British Crown Jewels, it
would be a revenue-neutral business.


SW


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"P & H Macguire" wrote in message
...
I am in the process of scanning some old slides of 60s to 90s and
wondered what the optimum size should be for posting on this N/G.
They will be scanned at about 300dpi.

Regards

PJM


Thanks to everybody who took the time. A lot of food for thought
there.

Regards

PJM

"P & H Macguire" wrote in news:yFe1i.14160$8E.416
@newsfe5-win.ntli.net:

I am in the process of scanning some old slides of 60s to 90s and
wondered what the optimum size should be for posting on this N/G.
They will be scanned at about 300dpi.

Regards

PJM


Okay.

To be technical, DPI is a printing resolution, and you cannot scan
at that. This is nit-picky, because the actual term for scanning
resolution is PPI (pixels per inch), and most people use them
interchangeably, but there is a difference.

For scanning slides, start at max resolution and try working
backwards on the sharpest slides, watching the differences carefully at
100% in your image editing program. This will largely appear to be
blotches of indistinct color, but you can see whether the higher
resolutions make any difference to your slides. Super sharp slides may
benefit from scanning at 2400 PPI or higher, but film grain, lens
quality, and steadiness of the photographer all play a part, and pics of
lesser quality may not show any improvement between 1200 PPI and 2400 PPI
because, quite simply, the resolution isn't there in the film.

For scanning prints, you typically will not pull up much, if any,
detail beyond 300 PPI. Magazine prints can typically go lower, but
scanning at a higher res with the page at a slight angle helps correct
for screening (moire) patterns, and the pic can be straightened after
scanning in your editing program.

I have never discerned any difference between saving in TIFF
(lossless) format and highest quality JPEG, except for the tremendous
savings in file size - this, mind you, is for the original scan. Archive
off the original scans and back them up - you never know when a slide
will get damaged or disappear. And always work on a copy. There's nothing
more frustrating than hitting "Save" instead of "Save As..." and
overwriting your original scan.

As for display resolution, you can ignore DPI entirely - it means
absolutely nothing to the monitor or display. My vote goes for 1024x768
pixels or smaller, because I'm one of those miserly people who maintains
that as a monitor resolution. Larger just means scrolling, and that
detracts from the affect of the shot, especially if you're the type to
frame a shot carefully.

JPEG compression seems to work just fine at between 50% and 80%
quality (100 being full quality, not compressed) - it depends on, not the
detail of the shot, but the gradients, which is where jpeg compression
has its first affects. If you see your skies becoming blocky in places,
increase quality.

Sharpening should be done sparingly, if at all. If you see halos or
fringing occurring along areas of high contrast, you're sharpening too
much.

More info than you asked for:

DPI is considered a printing resolution, but most printers nowadays
ignore it entirely and simply interpolate what is needed from the final
print size you indicate. Even the home inkjets will print far more than
300 dots per inch, but this is because they have to make a 16 million
color gamut from 6 ink colors or less, and have to layer in multiple tiny
ink dots to give the impression of a field of clear Prussian Blue.

About the only place I've seen DPI make any difference whatsoever
has been when you're laying text in over the image (like a copyright
mark). Photoshop, at least, judges font size on the DPI resolution, so
pick one and stay with it. It can be 1 DPI if you like, and the file info
may consider your pic to be a thousand inches wide, but it'll still
display one pixel per pixel on a monitor at 100%. 300 and 72 DPI are the
defaults, and either one works fine. Information like that is ignored by
both browsers and monitors, which only work from the pixel dimensions.

And in fact, even for web pages, the photo displays at the pixel
dimensions specified in the html, which may not be the pixel dimensions
of the jpeg file. Lots of novice web designers cause huge page loading
delays because they take a jpeg way too large for the web and "size it"
in the html. All it means is a large file takes time loading just to
display at a res that it could have been sized to in the first place.


- Al.

--
To reply, insert dash in address to separate G and I in the domain

"Al Denelsbeck" wrote in message
.128...
"P & H Macguire" wrote in
news:yFe1i.14160$8E.416
@newsfe5-win.ntli.net:


And in fact, even for web pages, the photo displays at the pixel
dimensions specified in the html, which may not be the pixel
dimensions
of the jpeg file. Lots of novice web designers cause huge page
loading
delays because they take a jpeg way too large for the web and "size
it"
in the html. All it means is a large file takes time loading just to
display at a res that it could have been sized to in the first
place.


- Al.

--
To reply, insert dash in address to separate G and I in the domain

Again, thanks to everybody for these very full and interesting
replies. I had no idea I was going to stir up such a hornet's nest!

Regards

PJM

"Pjmac35" wrote in message
...
Again, thanks to everybody for these very full and interesting replies. I
had no idea I was going to stir up such a hornet's nest!


Hornet's nest? good lord man, this is no hornet's nest. This is simply
a thread that got a few replies. You want to see some "hornet's nests",
check out some of the lengthy and vitriolic thread in
alt.binaries.pictures.military, or even
alt.binaries.pictures.motorcycles.harley. Them's some hornet's nests...
BTW, welcome to the group.


Luke

I had no idea I was going to stir up such a hornet's nest!

Of course that's an F-18 Hornet's nest.

"shiver" wrote in message
...
I had no idea I was going to stir up such a hornet's nest!

Of course that's an F-18 Hornet's nest.

No! A De Havilland Hornet of course!

Regards

PJM

Pjmac35 wrote:
"Al Denelsbeck" wrote in message
.128...
"P & H Macguire" wrote in
news:yFe1i.14160$8E.416
@newsfe5-win.ntli.net:


And in fact, even for web pages, the photo displays at the pixel
dimensions specified in the html, which may not be the pixel
dimensions
of the jpeg file. Lots of novice web designers cause huge page
loading
delays because they take a jpeg way too large for the web and "size
it"
in the html. All it means is a large file takes time loading just to
display at a res that it could have been sized to in the first
place.


- Al.

--
To reply, insert dash in address to separate G and I in the domain

Again, thanks to everybody for these very full and interesting
replies. I had no idea I was going to stir up such a hornet's nest!

Regards

PJM


Which hornet was that?

--
Moving things in still pictures!