Hi every one, these days when we talk about scanning, sounds just like photocopying, simple and easy. But the real factor is not. How good is your hardware/software and your skill do play a very important part.
I just want to provide some basic technical info, and help us to get more detail / better tone reproduction from our original.
Trans has a density range between 2.4 to 4.0, where colour negative is about D1.15 to D1.45 and print is D1.2 to D2.2.
Scanner has 3 distinct categories:
∑ Home / Office use = CCD Sensor. Low to Mid Quality. Limited Dynamic Range and Resolution D1.8 to D2.3.
∑ Mid Rane = Medium to High Quality. Dynamic Range - D2.5 to D3.5 CCD/PMT sensor.
∑ High End = High Quality. Dynamic Range - D3.5 to D4.3 PMT Sensor.
Among all of this, we will have resolution / sharpness differences. Although on paper manufacturer may provide similar same spec.
First you calibrate your scanner, then mount your original, enter parameter as require, and last press start button to scan. Just like copying machine, click and finished. Is that sound easy? But how many of us do satisfy our scan result? Or scan image is about as good as original?
I would like to give some simple tips behind the process. As we want to capture all or at least most of the gradation / detail / colour from our original, can our hardware/software capable of doing it? For your info: Most product in the market not able to achieve the quality. We need at least a med-high end scanner with good dynamic range, high resolution to do the job.
I use a drum scanner to scan my original "slide" and "print" because this unit can see through deeper shadow real optical resolution, and a maximum density of 4.2. Below is the procedure of how I do the setting up:
Mount original on the drum cylinder, (Trans use oil to mount)
Focus and calibrate white balance
Set the start and end scan point
Measure / check for the min/max density of the original, #
Measure and set up the gray balance for highlight /Midtone /shadow ##
Colour correction/adjustment###
Gradation setup and adjustment (Separate contrast adj for HL/MT/SD)####
Enter all value into the computer,
Set the scale of enlargement/resolution with proper aperture
Set USM signal strength *
Start to scan.
# Transparentcies can have a Dynamic range of D4.0 (14 bit) in most case, but our monitor or inkjet/laser printer not able to hold that wide range. 8 bit colour have 255 level of tone only (aprox D2.7 of dynamic range), printed material can hold to D1.8 to D2.2.
## Usually slide/colour print have a degree of colour cast. To maintain neutral colour gray, gray balance has to be adjusted or fine tune, to achieve best result.
###As inkjet ink/printing ink (colour is impure)do not absorb or reflect light same as colour dye that use in photography material, a level of colour adjustment is required to have a faithful reproduction.
####Base on our print/display devise, we may expend or compress HL/MT/SD tone range / contrast separately for different printing/viewing condition.
*USM = Unsharp Masking
No matter how good is the scan, compression of the density range cause the image to lose some sharpness and be less contrasty than the original. To compensate for such degradation, exaggerate the contrast of the edges of image and make it looks sharper.
Hope this can help every one understand a bit more in scanning their images.
Note:
Density 0 - 1.0 = Contrast Ration 1:10 = 4bit Depth(approx)
Density 0 - 2.0 = Contrast Ration 1:100 = 7bit Depth (approx)
Density 0 - 3.0 = Contrast Ration 1:1000 = 10bit Depth (approx)
Density 0 - 4.0 = Contrast Ration 1:10000 = 14bit Depth (approx)
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The reality is that while the differences between a drum scanner and an average film scanner are obvious, with proper post processing, the results end up a lot closer than most people (especially those who own drum scanners) would like to believe. Don't get me wrong; I'd love to own a drum scanner as the post processing is quicker since the original scan is higher quality. However, the point I'm making is that one can only get good at scanning by doing it first, making mistakes and then letting experience guide them. The reality is that most people don't need or care about spending uber-hours getting the most perfect scan imaginable (which doesn't exist). My basic technical info for people getting into scanning would be: 1) buy a decent flatbed scanner, 2) get good software to drive the scanner, 3) practice scanning and then 4) delve into the more technical aspects of scanning (if it's even necessary).
Originally Posted by jdimichele
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