Digital Lith Tutorials – Standard Process Parameters
In the last two 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.
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 us|ed. 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.
Highlight Contrast – With this parameter you gain control over the contrast level of the highlights. A value above one increases the highlight contrast whereas a value grater than zero, but lower than one decreases highlight contrast and thus also highlight definition. When you increase this parameter you may also want to decrease the exposure parameter, even into negative numbers. This parameter got introduced with version 4.5 of Digital Lith.
Slowdown Shadows – With this parameter you get control over the deep shadows as it slows down shadows the darker they get. This is a percentage. This parameter got introduced with version 4.5 of Digital Lith.
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.
Playing around with parameters
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. In the previous example, the image that you see is with a development time of 95. And as you may have realized, there is a lot of highlight detail in the image that is not yet showing up very satisfying in the lith image.
As in real lith we might want to increase the exposure to get the highlights catching up with the shadows. Let us start with a relatively high number of 5 in this case. You can see (first image) 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 since exposure value of 5 seems a bit over the top, let us reduce it to 3. With snatch I ended up with snatching I ended up at a development time of 90. The second image shows the result.
Next let us go with a little bit more lith grain. A higher grain value (0.3 in our case) results in faster development. So let’s go up with the dilution too and set it to 30. Keep the development time for now (or snatch it if you like). The result is shown in the third image.
OK, now let us deal with another parameter (or parameter pair if you like). It is the sulfite/bromide ratio. A higher amount of sulfite smoothens the grain. As you see in the third image, it got rather grainy, so let us smooth it by setting the sulfite to 5 instead of 2. But keep in mind: Increasing sulfite also means a speed-up in development. So let’s increase the dilution again, this time to 40 which might let us stay at 90 for the development time. See image four for the result of this development.
Now again, I do not think that the highlights look very promising and by just looking at the highlights and mid-tones we ended up with rather blocked shadows. So in our next run we are going to slow down shadow development a bit by setting the slowdown shadows value to 50 and the development time to 80. See the fifth image. This unblocks the shadows a bit but shadows are rather dull since the shadow contrast isn’t very good.
And this leads us to a parameter that I use all the time since it got introduced. It is the highlight contrast parameter. With Exposure, Highlight Contrast and Slowdown Shadows you are able to control contrast in you image to a degree earlier versions of Digital Lith were not able to. So let’s give it a try. Just remember, you need to play around a bit and get used to all these parameters to get the results you want. There is no free lunch. But to make a long story short: The highlight contrast value and the exposure value depend on each other a bit. So when increasing the highlight contrast you will very often go into the negative values with the exposure value, just to preserve shadow contrast too. And since you shadows might block up then too fast you will have to use the slowdown shadows parameter to get differentiation in the shadows again. Once you’ve done this a few times it becomes second nature. Here we go with the following changes wrt. the last development: Highlight Contrast (5), Slowdown Shadows (75) and Exposure (-2) and see the last image for the result. You can download these settings as a preset at the bottom of the page.
- 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.
- Deal with highlight contrast, slowdown shadows and exposure values to control highlight and shadow contrast
But now that you may play around with different development parameters it is time to look at how to store them in presets: Click!