Why use ColorNeg?

ColorNeg provides similar advantages to using a RAW converter in digital photography when working with your negatives. To be able to harness these it is important that your negative scan is linear and completely unaltered. This means that the initial image file must resemble exactly what the scanner's CCD read in. Such scans are sometimes also referred to as RAW scans. To find out how to produce such scans with various scanner software and models please visit our section on obtaining linear scans.

Black and white negatives nearly always contain more information than can be reproduced in a positive image without taking special measures. If you have your negatives inverted by a scanner software you are likely to loose valuable detail and will be able to exert close to no control in the process. On top of that it is highly likely that your scanner software uses the same incorrect inversion technique as Photoshop does. ColorNeg offers you correct image inversions with a maximum of control and provides the means to convert your monochrome negatives in different ways that closely resemble working with photographic papers of varying grades.

Why not simply convert monochrome negatives using Photoshop?

As we have illustrated before the assumption that a color negative's orange mask is to blame for inferior conversions in Photoshop is wrong. Any such mask can be removed easily enough. What really is to blame for the inferior quality in inverting negatives using Photoshop are wrong calculations. Photoshop's invert command will subtract the value that is to be inverted from the maximum value possible. For this method to be correct the negative's intensities would have to be additive which they are not. What is additive instead for photographic film are densities. Assuming we are working with a linear scan in Photoshop the invert command is being applied directly to intensity values, while it should be applied to density values instead. The addition / subtraction of such density values equals the multiplication / division of intensity values. What this boils down to is that Photoshop subtracts where it really should divide. If you are interested in a complete mathematical analysis of this issue please feel free to study our technical report Negative to Positive. Photoshop's incorrect approach in calculating inverse pixels will inevitably lead to inferior monochrome conversions. The negative effects are less obvious here than they would be for color images since monochromes as such mean a greater degree of abstraction from a natural representation of a scene. We have prepared the following comparison to prove our point visually.

 

To illustrate the possibilities and limitations within Photoshop itself let's first adjust the following linear scan of a monochrome negative to windows' system gamma of 2.2. This setting is what is used for image files encoded in many common color profiles like Adobe RGB 1998 or sRGB. Therefore this is what we would most likely deal with when working in Photoshop.

Our monochrome negative does not contain any colored mask and should be easy to convert. Nevertheless the command Image / Adjust / Invert creates a very dull positive. The image created already contains very deep blacks and can now be adjusted using the levels tool in a way that lets it get as close to containing pure white as is possible without clipping any highlights.

Since we know the gamma value targeted in developing the negative we have a rough idea of how to adjust the mid tones to achieve what should be a natural representation of the scene. While the same adjustment would work out perfectly for a correctly inverted negative as we will see in just a moment the incorrect inversion technique used in Photoshop and the anomalies when adjusting the mid tones shown in our technical documents have taken their toll. Simply applying the correct gamma value to achieve the most natural reproduction will not change the effects of the incorrect inversion. This will become even more obvious when comparing the version created in Photoshop to a simple conversion in ColorNeg that uses the same settings for Gamma.

Since the gamma value of monochrome images may be adjusted as needed for artistic purposes you might ask if it would not be possible to achieve the same result using Photoshop. By changing the gamma value in the levels dialogue to a rather extreme setting it is indeed possible to produce a version of the image that more closely resembles the mid tones of what we have created using ColorNeg. Matching the quality of the highlights and shadows is impossible though.

The conversion made within seconds using ColorNeg is clearly superior to the best version achieved using the cumbersome process in Photoshop alone. The greatest problems of the positive created in Photoshop lie within the shadow and highlight regions of the image as we will illustrate in the following two details:

Detail 1: Photoshop; ColorNeg, Detail 2: Photoshop; ColorNeg.

It is even possible to further improve the quality of the quick conversion created with ColorNeg by combination of a second conversions using a different virtual grade. The two conversions have been created separately and were then blended in a suitable way using Photoshop. This technique resembles an elaborate combination of burning and dodging in the darkroom combined with using different grade filters on the respective areas of an image printed on multi grade photographic material. Please go ahead and compare this version to the one created in Photoshop once more!

Why not invert utilizing Photoshop's Curves?

Some B&W photographers use techniques involving the Curves dialogue in Photoshop to invert their negatives. While it is indeed possible to get closer to the real thing that way the results will not match the quality of a conversion with ColorNeg. This is due to a limitation in Curves itself. While Curves works on 16 bit/channel images, the points defining the correction curve are limited strictly to 8 bit 0-255 values. This is simply not sufficient to reproduce important parts of the curve required here.

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