Digital Lith Tutorials – Pepper fogging and patterns

In this episode of the Digital Lith tutorials we are going to have a closer look at uneven development. This will be a two part Section and we start with Patterns and Pepper Fogging which means this part of the parameter section shown below on the right.

When doing lith prints, depending on the paper and developer setup you use it may happen that you get uneven development effect. Lith printing is vulnerable to inconsistent move of the developer tray. So you may get streaking and maybe under developed parts. Lith printing also easily reveals emulsion faults where the normal process just runs smooth. And then you may also have to deal with chaotic infectious development also called pepper fogging. Pepper fogging usually is controllable although there are papers where this is easier as with others.

Let’s start with pepper fogging first since this is just one single parameter. It is given as a percentage. That means you specify the percentage of the image area which will show pepper fogging. Usually this will be a very small number, way below one percent. The following images show increasing amount of pepper fogging (1/10000%, 1/1000%, 1/100%)

Pepper fogging is applied to the image at the beginning of the process so the fogging gets developed and dots will grow in size – which explains why the 1/100% image does not really look like 1/100%.

Usually pepper fogging is something that you want to avoid and it is added to Digital Lith just for fun and completeness. I for example have it switched off in the preferences since I never use it – except for these demo images.

Next part of this episode is the pattern overlay. Here you provide a set of patterns that you can choose from and then this is added to the image before processing. It is added to the paper layer only and so it is different from applying the pattern to the image before loading it into Digital Lith.

To work the tutorial you can create a directory on your filesystem and then in the preferences point the pattern directory entry to this directory. At the bottom of this page you can find two zip files for download. Please unpack them into your pattern directory preserving the subdirectories – this means after unpacking the two files your pattern directory will contain two subdirectories called PaperCrushed and PaperCrushedSmooth. Each of the two subdirectories will contain two patterns.

Now, if you click on the Pattern type in the uneven development part of the parameter panel you will be able to select between the two pattern types. 

The patterns are organized into pattern types. As you already know from installing the demo patterns, on your disk this means there is a pattern directory that you specify in the preferences and then you have the patterns organized in subdirectories which correspond to the pattern type. I have a whole set of images of crumpled paper which I have in original and smoothed versions in different directories. One example would also be to have different grain patterns and so on. For example you might photograph a gray cardboard with film and then scan the film and store that as a pattern to have the grain structure applied to the image. So the pattern type is the directory name of the subdirectory and the pattern name is the file name of the files found in that directory. There is no other configuration file needed for this. The image on the left shows how this might look like.

Once you select a pattern you need also to give a pattern strength (which corresponds a bit to the grain value of the standard process). Then in addition to that you might want to do some transformations like rotate it or flip it horizontally or vertically. There might be more transformations to come.

Since the overall brightness of your patterns might be different you may check auto-contrast which will adjust the pattern so that its values will range from bright white to pure black and the average brightness will be a middle gray. That way you can change the pattern without adjusting the strength or any other development parameter to match the pattern brightness.

And last but not least you can also invert the pattern.

Let’s look at some examples. We start with the demo image, reset the development parameters and apply the coloring preset to have the same coloring. Patterns can be quite aggressive if the bromide is high. So let us adjust the development parameters a bit and set the sulfite to 5, the dilution to 30 and the development time to 85. Do not select any pattern yet – we do want to have something to compare to. See the first image below.

Then since we add a pattern increase the dilution to 40 and select the pattern type PaperCrushed with pattern name img002. This will set the pattern strength to 0.1 – keep it. The result can be seen in the second image below.

Next let us try the effect of auto contrast. Select that option and keep everything else the same. See the third image below.

And next we also check invert – as above, keep everything else and you should get a result similar to image four below.

Now that crushed paper patterns might be a bit hard to accept – it is a matter of taste anyway. To get an impression of uneven development it is better to go with smoothed out patterns. Let us try this by selecting pattern type PaperCrushedSmooth and again with pattern name img002. And we do not invert this time. The result can be seen in the fifth image.

OK and last but not least, since the images went a bit dull, let us bring a bit of contrast back. For that we increase the highlight contrast to 2 and the exposure to -1. Go with the dilution back to 30 and let us also get some slow-down and contrast by increasing the bromide about by 2% in each iteration. You can download the preset for this at the bottom of the page. The result is the sixth and last image below.

As you can see, there is a lot of room for creativity here. Play around with it and make sure that you do not end up walking around and looking for patterns only.

This completes the episode about pepper fogging and pattern overlays. The next episode will throw some light on streaking modules which is another way to have uneven development effects simulated. Here you go: Click!

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