On 8/1/09 22:29, "aussieshepsrock" <ilovaussiesh...@yahoo.com> wrote:
> HiYa Pete and Everyone,
> My intended Scanning Methodology - Seperate from my Media Storage
> Options - is something like this. I've only done a 50 image or so
> 'test' run to sort out file size and physical process considerations
> at this point. Some of this is based on some comparative tests of
> various 'scanner driver' options.
>
> TIFF with internal compression OFF
> Photograph Fronts:
> 600 DPI Resolution
> 24 BIT Color Depth
> Digital ICE OFF - It's mucking much more than it's fixing.
> Unsharp Mask (in scanner software) at the High Setting because it
> appears to be a well behaved and subtle implementation in my testing
> up to this point.
>
> Photograph Backs:
> 300 DPI Resolution
> 8 Bit Grey Scale
> Unsharp Mask set to High
>
> All images receive Levels Adjustments Set Manually. The sliders for
> each color channel are tweaked individually so the sliders are just
> past the Highest and Lowest Point on the Histogram Display for Each
> Channel - ie the darkest/dimmest value is changed from zero to 9 if
> the scans histogram shows no info below 10. I am cautious about
> overpowering a particular channels level adjustments and making an
> image look 'wierd'. I believe this is called manually clipping the
> highlights and shadows. I can find very little 'standards or good
> practices' info via google or yahoo searches. This is just how I've
> learned to go about getting good scan results since my first encounter
> with a grayscale only flatbed back in the early nineties!
Well you seem to have quite a job on so here's a few tips. The optical
resolution of your scanner - say 600x600ppi for this purpose - is the limit
for original capture - higher resolutions like 9600x9600ppi can only be
provided by interpolation (guesswork from maths) and do not contain more
detail from the original. So the lowest optical res of your scanner should
give you your basic max scanning res - a 1200x600ppi scanner would be 600ppi
- over and above this res you are only adding original data in one direction
in the other direction the scanner is calculating the data - above 1200ppi
it is calculqting the data in both directions. Unsharp masking is better
done selectively per image in Pshop if you have it as ramping the edges to
provide a sharper image can produce artifacts.
Levels is a destructive process which affects the entire image - if you
move the black point or white point by 10% you are not only disposing of 25
channel levels from each colour - you are creating 25 new ones for each
colour as each channel must have 256 levels. I use the non destructive
curves if at all possible and reserve level adjustment for very poor low key
originals.
Highest resolution? I would say around the 200/300ppi mark unless they
are earmarked for substantial enlargement. The human eye can only resolve
around 180 levels, b/w newspapers print photos at around 80 lines of dots
per inch (the cheap paper limits the res) and we see them well as images.
Glossy colour mags 133/150/175 lines of dots per inch and they look very
acceptable even though the CMYK space is smaller than RGB. Computer monitors
are limited by dot pitch and can only manage hardware res around 90ppi so
any res above this is a software representation - tv's are worse with poorer
dot pitch.
My archive of high res images is stored at 360ppi, medium res at 180ppi
- the odd numbers are due to my printer being an Epson inkjet which has a
printing resolution divisible in both directions by 180 (5760 x 1440dpi) and
the print results are much better and faster than if I ask it a difficult
resolution recalculation - which it doesn't seem to be very good at - indeed
the prorietary print driver's ability to convert well from RGB to six colour
CMYK has always annoyed me - and b/w printing is awful - hopefully improved
with their latest set of 8 colour printers - with three blacks. Black and
white commercial printing of photographic images has always been a problem -
solved usually by the use of duotone or tritone. If you come across a book
of Bresson's work or Adams have a look closely with a magnifier - the b/w
photos will probably be two or three colour.
Finally I would add the fact that re-resing is always possible with a
good image editor - a 200/300ppi digital image can be easily upped to
1200ppi without problems. The image editor is simply doing what the scanner
does over and above it's optical resolution - interpolation - but probably
doing it much better in the case of Pshop.
Pete
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