Optimizing Scanner-Side Colour Settings

Especially useful when archiving poor quality originals

I have been scanning for 20–25 years and just clued into the value of this concept a couple years ago. I have gone so far as to go back and rescan a lot of my old images since. Some are much improved, and others hardly seem different. A poor original is still going to elicit some frustration. Basically it will depend on the depth of colour in the originals I think, and how much data there is in the light/dark “ends” — or something of that nature. I am aiming for Good Enough, with minor steps taken to optimize results.

Naturally I can only show you what the settings look like on my setup, so you will be applying these concepts to your own scanner’s software.

* * *

First, make sure your scanner has been calibrated, with nothing on the platen. It is not necessary to do this every time, just once each time scanning software is installed or reinstalled, or if it accidentally gets recalibrated with something on, which would throw it off. It expects white/blank for calibration {or if more sophisticated with a specific colour chart and third-party calibration software}.

Then adjust for a specific colour balance for each scan. If there is an “auto tone” setting that might blow out whites etc, so a manual method gives better control. It is worth the time per scan, for me.

Your scan software will likely look different from these screen shots, but the information can be extrapolated and you will need to find your colour level settings. My software is the Epson Scan that came bundled with my now ancient Epson Perfection 4870. If you have a choice between curves and levels, I recommend levels. I find curves control better for touchup after the fact, there is more nuance for each channel. For scanning settings I find levels more straightforward. Of course you may want to experiment a bit and find what works best for you.

~
Here is the setting I get when default settings are “Reset” {in my software’s terminology}. This is different from an auto-tone setting. In this example, the marquee has been drawn around the whole thing, with a little room outside the photo edge to reveal the platen. {Incidentally, I just concentrate on the Channel portion of the levels adjustments — grey balance etc. all gets ignored. This tutorial outlines a fairly quick method. There is a lot of room for getting very fussy, and I say, more power to you if you want to do so.}

1_default_no_auto

Straight result — I’ve posted a touched-up version of this at the end for comparison.

1_default
~
Pull in the marquee so it is only reading the image portion. This cleans up the shoulders in the levels histogram. This marquee action is for setting input colour levels only, you’ll pull them back out to where you want them before actual scan. Platen colour and “white” edges, or slide casing would be off the chart for some images, and give a compromised histogram reading, in relative terms.

2_pull_marquee

I adjust the RGB first and then tweak each channel individually. Probably I might be wasting time with the first step [RGB] but it’s an old habit now…

3_tighten_rgb

This gets it closer but the individual channels are not clean — not in my software, and so far not in any that I’ve seen. The best piece of this-level scanning software I know of is Silverfast, but even at ~50$ it is too rich for my blood, and the percentage of improvement is not enough over what I have using a free bundled software. Your capture software that comes with the scanner is usually robust enough and just fine. {If my operating system ever boots the Epson Scan software out, I will probably purchase the lowest-end version of Silverfast, presuming I am still physically able to hook up the old workhorse…}

You can see here the red channel would lose detail at the white point. This is what typically happens in one-touch auto-tone settings, but perhaps a bit finer per channel. Needless to say you can’t get back detail that was never captured.

4_r_tighten_starter

Adjusted:

5_r_fixed

~

Lather, rinse and repeat for each channel.

With all three channels adjusted individually, as above:

6_all_channels_adjusted

~
The straight scan with these settings — no touchup:

7_straight_adjusted
~
Original {default or “Reset” spectrum}, touched up:

1_default_TU
~
Scanned with manually adjusted settings, and touched up lightly. I can go bananas and really fine-tune the touch-up, but this gives a good idea. This original is pretty blown out, which is why I picked it as an example. So the above {“default”} looks more yellow and the greenery is very green — The adjusted scan is a little lighter but the colours are quite a bit more natural. This one is never going to look that good with virtually no detail in some of the channels, but touching up a pre-adjusted scan is a lot less maddening, allows for finer control, and yields more natural colours.

carnahan_girls_diving_board_1968

Full disclosure: I added detail to the black channel for both of these {I touch up in CMYK and then re-output RGB, it is just a throwback to preparing scans for 4c printing}.

* * *