(updated 7 Mar 2013)
Some time ago I wrote an article about getting the most from colour negative scans with VueScan. Since writing the article my workflow has changed significantly, and these are the main reasons why:
- It takes far too long to profile the film base colour using VueScan, scanning isn’t fun at the best of times and I’m an impatient person.
- I’m now shooting a lot more colour slide film, and wanted something that would work equally well if I needed to tweak colour.
- I’m shooting 8×10 & 4×5 sheet film which doesn’t have an area of clear base that I can sample.
- I realised that the old method didn’t stop me having to tweak colour in PhotoShop, and that often the output was worse than from a film preset.
By chance A friend, Raoul Gatepin (Who is an awesome photographer) introduced me to the PhotoShop plugin, ColorNeg, and since then I’ve not really looked back.
ColorPerfect is the latest incarnation of ColorNeg (it amalgamates ColorNeg & ColorPos for slide film) and is the plugin I use on a daily basis, I’ll do my best to describe my workflow here using both text and imagery.
Note: this article does not cover Screen or Scanner profiling, both are critical to good colour workflow, it’s particularly important to ensure your screen is profiled otherwise how will you know if you are making good colour decisions?
For ColorPerfect to work at its best we need to ensure that VueScan does not do any image processing on our scans whatsoever, for this reason we must save our scans as 16 bit RAW Linear files. Before going any further with this article you will need to own a licensed professional version of VueScan otherwise RAW output is unavailable.
I’m also very much of the opinion that sharpening, dust removal, etc should be done selectively and by hand in PhotoShop so I disable things like ICE & sharpening, here’s a quick run through of how I think you should configure VueScan.
The first thing I turn off in viewscan is the automatic saving of scans – I often find that the scan shows an imperfection that the preview does not, meaning I’ll discard the scan, so why waste disk space keeping a copy?
Although we’re going to save our scans as RAW files it’s important to keep VueScan’s Media setting configured to ‘Color Negative’. With this setting enabled VueScan scales the output of each colour channel so that they are roughly the same. There is typically 1 EV difference between each channel with red being brightest and blue darkest.
Increasing the number of samples helps to eliminate noise in the shadow areas of the scan, obviously the more samples the longer the scan will take so I opt for 3 as a minimum number to average out error.
Next you need to untick every format except ‘Raw file’ on the Output tab, be sure to leave Raw DNG unticked! Set the ‘Raw file type’ to ’48 Bit RGB’. I also like to set Printed Size to ‘Scan size’ to stop VueScan resizing the output.
Now that you have a baseline configuration for ColorPerfect you should save it for future reference. It’s time to start scanning.
Once you’ve scanned, saved and opened your image in PhotoShop you should have something looking a bit like this:
The orange cast of the film base is very apparent, next you need to assign a reasonably wide gamut colour space to the scan so that none of the colour information is lost, I usually opt for Adobe RGB. Once you’ve done that you can start the ColorPerfect plugin via the Filter menu in PS (Filter->CF Systems->ColorPerfect).
I’ve deliberately chosen a difficult film stock here, it’s a cheapo Boots Chemist 200 speed film, most branded films are a doddle to colour correct because the film preset is obvious but in this case some internet searching showed the film to be a Fuji rebrand. So with this in mind I simply chose the film base that gave the most natural looking colour – although you can see that there’s a slight magenta cast to the sky/neutrals.
You’ll notice that I have ringed the three areas of importance in red, film brand, film type, and gamma input mode. The Gamma Input mode should always be set to L for colour negatives (which should always be Linear 16 bit scans), the other setting of G is for use with positive files produced from Slide Film. It’s best to use a gamma C setting of 2.2 for negs. Also always set the ‘specific’ mode to ‘Clear>Initial’ otherwise the plugin will use the settings from the last time it was used in this mode.
Again, this film stock is generic, and although we know the approximate brand we’ve no way for sure to know the actual film type. Even when we know the brand and stock, individual batches can be quite different from one another. The development process throws even more variance into the mix. In short, it’s quite obvious that the inbuilt profiles may never actually give us the best match when we know a film stock, let alone when we don’t. This is where a great new feature of ColorPerfect comes to the rescue, it’s a feature called Filmtype
You can see in the screenshot above that I’ve selected the ‘FilmType’ setting in the main dropdown. All that you need to do after this is find a neutral gray area in your image and click on it. For this photo I clicked about in the grey parts of the cloud until the overall balance was as close as I could get it. Now here’s the nifty bit, by dragging the main slider up and down ColorPerfect varies things just slightly, and typically somewhere in the entire slider range you’ll hit the sweet-spot. You can fine tune thing even further by clicking on the ‘FilmType’ button, this will toggle into ‘SubType’ mode; adjustments of the slider now makes even more subtle changes.
Things still aren’t quite right, the contrast looks a little off, so now it’s time to adjust Gamma.
Change the main drop down setting to Gamma, then simply adjust the main slider until the blacks look about right. That’s it. Often these changes may be marginal, but it’s what feels right that is usually best.
So now that I’m happy I simply click ‘OK’ and use PhotoShop to ultra fine tune colour and levels.
Another great feature in ColorPerfect is the ability to compress the highlights in your image, essentially, this stops highlights being blown when you are trying to boost shadow detail. This is important because although colour negative film has a dynamic range which is often in excess of 14 stops, a typical positive image (be it on screen or print) has far fewer. Naturally you’ll need to represent as much of this information as you can but in a non linear fashion.
The above example exhibits significantly blown highlights. I’ve ringed the highlight compression box, this consists of 3 settings, these are, from left to right: the number of stops correction(or off), range of values, & the image percentage being blown out/clipped. So, for this example you can see that the compression is off, the range is 220 (default), and the clipping percentage is 18.86%
Simply by setting the compression range to 0.2 stops I’ve reduced the percentage of blown out pixels from 18.86% to 7.3%. I’ve deliberately chosen to leave a reasonable percentage of blown pixels because otherwise the image can start to look pretty flat. I believe that blacks and whites should almost always be clipped to some extent – have a play with the feature yourself and see what looks best to you.
Working with slide film is essentially the same as working with negatives, but the main difference is that colorperfect must be set into ‘colorpos’ mode and a gamma mode of G. Usually the gamma mode of G is automatically set when switching to colorpos mode, but it’s always worth checking. As with negatives, I always also make a point of setting the ‘specific’ mode to ‘Clear>Initial’ otherwise the plugin will use the settings from the last time it was used in this mode.
When I’m finished with the image in ColourPerfect I may want to fine tune some things, usually this will be levels work and fine tuning of colour. I must admit that I find the PhotoShop interface much more intuitive to work with than that of ColourPerfect so I tend to use it for fine tuning even though most of this can easily be achieved in the plugin.
Firstly I apply a ‘Levels’ adjustment layer (Layer->New Adjustment Layer->Levels…)
Next I correct any overall cast by adjusting neutral colour balance with a ‘Selective Colour’ adjustment layer (Layer->New Adjustment Layer->Selective Colour), in this image you can see that the greens have a bit too much magenta in, so I remove as many points of magenta as are needed to achieve a good overall balance to the greens:
Finally I adjust sky colour by making a white colour collection, you can see in the screenshot below that I had to drop out some magenta and boost cyan. The key is to always try and make the smallest corrections possible otherwise you can end up with clipping somewhere else in the gamut, and that normally leads to posterised colour.
As I mentioned above you can also make these adjustments within ColorPerfect using it’s colour correction (CC) filters – however, one benefit of doing this in PhotoShop with a selective colour layer is that you can easily revisit the adjustment layer to make changes. ColorPerfect is what I term a ‘destructive’ process, by this I mean that once you click OK you can’t go back without starting from scratch on the original scan.
And that’s pretty much it for PhotoShop other than any selective contrast and sharpening work I would normally perform
ColorPerfect saves me a lot of time when using VueScan. Before my use of ColorPerfect I had to perform time consuming exposure locking and film base colour sampling all because VueScan has very limited film profile support. Even after carrying out these long correction procedures, I was still having to fine tune colour in PhotoShop: and sometimes it was more course than fine tuning.
So now I have the best of both worlds, I can use my preferred scanning software, and spend minimal time in post production. I figure I spend about a minute per image correcting colour, and ColorPerfect is usually just a few seconds of that time.
I am quite sure that far more can be done with ColorPerfect, and I’ll update this article as I discover new techniques, and perhaps offer contrasting views if I believe that the same can be done more quickly in Photoshop. If I had one wish, it’s that ColourPerfect could be an adjustment layer rather than a plugin. But nothing is ever perfect.
I do hope that this is of use to some of you and please remember that you’re very welcome to post your own workflow and process improvement suggestions right here.