Digital Lith Tutorial - Standard Process Parameters

image

In the last few episodes we did developments without really knowing what all the parameters are meant for. Now we are going to have a closer look at all those development parameter. But keep in mind, this just covers the standard development parameters, there might be process modules installed with totally different parameters or parameters with the same name, but different behavior. Let us walk through them from top to bottom:

Development Time

Digital Lith is an iterative process where at each step the image is computed out of the step before. The Development Time defines the number of iterations. If you give a number greater than zero this defines the fixed number the process should run. But you can also have to process run until the first pixel does just not turn into full black. In that case you set the development time to zero. If you want to go one more step than that set the development time to -1, for two iterations more set it to -2 and so on.

The Development Time is a parameter which is independent of the selected process module. Whatever process module you are going to use, it will always be an iterative process.

Process Selector

This lets you select which process module to use. If there is no additional process module installed, then the selector is not shown.

Dilution Time

Digital lith is an iterative process and an exponential process too. That means the effects from one step towards the next might be quite strong and to have a better control on that you can define an iteration step from which on the development runs with a higher dilution. With this parameter you specify from which iteration step on you run with a higher dilution. If you do not want this to happen, set it to 0.

Dilution Factor

With this parameter you define the factor by which the dilution is increased once the dilution time is reached. A factor of 1 will have no effect.

Area Size

Digital Lith is a process which run with some locality. In the darkroom process the process runs faster where there is a silver grain seeded. To simulate this behavior digital lith runs with some locality. That means to compute a pixel also an area around it is used. This parameter gives the radius of this area. The area is going to used weighted so that those pixels with a greater distance will have less influence.

If you give an area size of 1 then the area used will be the 3×3 matrix around the pixel. A size of 2 will result in a 5×5 matrix and so on. Having a bigger area will slow down the process since there is more work to do.

One exception is area size of 0 where there is a 3×3 non-weighted area used.

Midtone Gradient

To have at least a little bit influence on the gradient you can define the midtone gradient which lets you adjust contrast of the image. In cases where you use an image right out of the camera this might be a good way to increase or decrease contrast. A value greater than 1 increases contrast, a value smaller than 1 will decrease contrast. The value has to be greater than 0.

Bromide Increase

As in the real process bromide will slow down development and increase shadow grain. In the real process bromide will build up in the developer during development. This parameter lets you simulate this. You specify the percentage bromide will be increased from one iteration to the next. Set it to 0 to run with constant bromide.

Dilution Increase

Also the developer dilution might change slightly when developing an image as the developer gets weaker over time. With this parameter you can simulate it. What you specify is the percentage the dilution increases from one iteration to the next.

Exposure

In the darkroom process you control image contrast by the amount of over-exposure you give to the image. The more light you give to the image the better the highlight tones catch up with the shadows. This parameter is the corresponding in digital lith and the behavior is the same, the highlight tones catch up if you increase it.

Dilution

This is the developer dilution. Increase it to have the process running longer. This influences how grain builds up as that effect is more pronounced if there are more iterations run.

Grain

To have infectious development started digital lith lays down a grain patter over the paper layer. This should be a value between zero and one. The higher the value the coarser the grain. With this parameter you are able to simulate a little bit the behavior of different papers. Use a low value to have digital lith produce effects that you may get with finer grained papers like Fomatone. Or increase the value to have digital lith simulating more grainier lithing papers like Adox Vario Classic or Fomabrom.

Sulfite and Bromide

These two parameters belong together and so will be described together. Bromide will slow down development and makes the grain coarser whereas sulfite will speed up development and make the grain smoother. These two parameters are tied together as they define a ratio and not absolute values. That means that the effect of setting bromide/sulfite to 2/4 is the same as setting them to 1/2.

Now that we have described them all let us try to go back to the image from last episode and experiment a bit with it. As you may remember, there is a lot of highlight in the window area. So here we might want to increase the exposure to get the highlights catching up with the shadows.

We start with a rather high value of 5 in this case (top left image). You can see that this also brings in the midtones – and far too much, so we will have to decrease development time. You can do this by using the snatch mechanism. And here we end up with decreasing the development time from 100 down to 90 (top right image).

Next increase the grain. Higher grain value (0.3) results in faster development so go up with the dilution (30) and a development time we will come up with the bottom left image below.

And now another adjustment, this time the sulfite value (9) and another increase in dilution (40) will lead with a decrease of exposure (3) and a development time of 65 to the bottom left image.

image
image
image
image

So here is what you already learned:

  • Increase the dilution to slow down development
  • Increase grain for coarser grain (will speed up development too)
  • Increase sulfite for finer grain (will speed up development too)
  • Increase bromide for coarser grain (will slow down development too)
  • Increase exposure to get the highlights catch up with the shadows.

But now that you may play around with different development parameters it is time to look at how to store them in presets: Click!