Best Free Software for Creating Digital Negatives

[thefizz]

Sorry if this has been asked before but I'm looking for suggestions on easy to use free photo editing software for making digital negatives for silver printing and cyanotype, vandyke etc.

 

[koraks]

I think you need to break down the question into three functions, and then decide how you want to distribute these functions across one or more software tools.

The functional areas would be:
* Editing the photos to get the look you want
* Applying the correction curve to 'calibrate' the digital inkjet negative to the printing process
* Sending the linearized image to the printer

It's possible to do all of this in a single suite, such as GIMP or Photoshop. Use curve adjustments (and whatever else you fancy) to get the look you want. Determine a linearization curve and apply that to the image. Then send the image to the printer stright from the photo editing suite.

But you could also split it up. For instance, do the editing in GIMP or Photoshop. Then use e.g. QTR (if you use an Epson printer) to apply the linearization curve and print the image.

Determining the linearization curve (i.e. the 'calibration') part is the challenging bit from a technical viewpoint. There are a couple of approaches for this, including Precision Digital Negatives, Easy Digital Negatives (ssl certificate expired on their site), Calvin Grier's Calibration series, TruNeg or workflows based on QTR (e.g. Richard Boutwell's B&W Mastery). Note that this is a non-exhaustive list. Most of these rely on some form of density measurement on a step wedge, on the basis of which the adjustment curve is created. You can also eyeball a curve and iteratively adjust it. I personally don't recommend the latter as it tends to be time-consuming and the risk of tailoring the curve to one particular (set of) test image(s) is very big, resulting in problems later on.

It's important to note that when it comes to linearization/calibration, part of the equation is the software tool, but a more important part is the conceptual underpinnings. The options I mentioned above differ in terms of these underpinnings and mostly also in the software tools they use to put the concept into practice. I mention this because it's not so much about the question "which software", but more about "which approach" works best for you. I recommend reading up on the options I linked to and see what resonates more with you. Personally, I learned a lot from Calvin Grier's approach, which coincidentally uses virtually zero custom-made software and relies entirely on Excel and Photoshop. In practice, when I (rarely) want to linearize something, I print a step wedge, take some density readings and then determine an adjustment curve in Excel, without relying on any of the tools I mentioned (but of course applying what I gleaned from all).

As said, density measurements taken from a test print are essential to most of these approaches (with the exception of TruNeg). These measurements can be taken in a number of ways: using a reflection densitometer or photospectrometer, using a digital image acquired with a flatbed scanner or even simply using the pipette tool on a digital photo of the printed step tablet. Use what you feel comfortable with and what your budget allows. You can probably get pretty far with the camera on your smartphone, if all else fails.

 

[Alan9940]

If you use PS, probably the easiest would be to go here and follow the instructions:

Digital Negatives (LUT)

www.bostick-sullivan.com

 

[thefizz]

Thanks koraks, lots to digest there.

 

[largo]

It's important to mention that some dig negs systems -- whether free or not -- force you to use a given operating system, while others don't depend on a particular operating system: for example QTR + QTP will force you to use a MacOS system, while EDN works on the web! (QTR alone works on Windows but suffers of issues on this system, and QTP works only on MacOS)

What's more, some dig negs systems require you to have Photoshop, while others do not: for example, ChartThrob requires Photoshop, while EDN does not. In theory, QTR+QTP does not require Photoshop.

This is an important point to bear in mind when assessing the cost of a dig negs system...

QTR = QuadToneRIP
QTP = QuadToneProfiler (Richard Boutwell's software suite)
EDN = Easy Digital Negatives (Peter Mrhar's software)

PS: In fact, any Photoshop .jsx script could theoretically be rewritten in JavaScript (and run on the web).

 

[koraks]

QTR alone works on Windows but suffers of issues on this system

What are those issues? So far, it seems to be doing OK, within the inherent limitations of QTR as such (see my earlier comment on its wayward linearization engine). I've been using it, on and off, for about a decade. I've never used QTP, btw.