Easy Digital Negatives

The manual – Easy Digital Negatives Script – EDN v.1

Easy Digital Negatives Script

Now that we know some theories about digital negatives and how to manually create negatives, there follows here almost a bonus chapter, which describes how to use the free program or script Easy Digital Negatives, which does all that has been described almost automatically.

The script works in Adobe Photoshop starting from version CS3 upwards, and in Windows as well as on Macintosh computers. Since the program is free and is not part of this book, I ask you to forgive me for any errors in the program. In short, take it as my gift to you who have read this book almost to the end.

Note. All files and program Easy Digital Negative, which is designed to automatically produce corrections for digital negatives, can be found online at Download page.

The purpose of the script

The Easy Digital Negatives script was basically intended to verify my theory about the benefits of mapping versus the use of the custom curve (see Mapping the mid-tones). Later on, I reworked the program to automatically produce digital negatives and to calibrate the computer monitor.

Work in the program takes place step by step and is composed of three basic operations. In the first section, named Method (1), we decide between the two procedures of mapping or custom curves. The third method allows the automatic creation of the Gradient Map layer, which is used for the above-described automatic calibration of a computer monitor.

Once we choose one of above-described procedures, we must decide in the second section, named Grid size (2), which size of grayscale step wedge will we use, either a wedge with a small 10 x 10 grid or larger with a 16 x 16 grid.

In the third step is a group (3) of selected basic operations (Choose operation), where we choose which operation will be carried out over a selected grayscale step wedge. We can automatically produce a mapped correction (or custom curve if this was previously selected), we can calculate the average value of a different grayscale step wedge’s correction result, or choose to combine basic adjustments with other, more precise correction in a mapping or custom curve layer.

All of the calculated corrections are saved by the program in separate files that can be loaded before printing negatives in Adobe Photoshop.

As the processes of mapping is the same as making curves, we present here only a mapping and just a brief description of the adjustments with custom curves.

Installing the script

Because the program is basically a script that is implemented in Adobe Photoshop, we must first load the script to the program Adobe Photoshop.

  1. First we close the program Adobe Photoshop.
  2. Then we copy the file EasyDigitalNegatives-v1.jsxbin to the folder of Photoshop scripts. This is most commonly located on the hard drive in the directory C:\Program Files\Adobe\Adobe Photoshop CS4\Presets\Scripts\.
  3. The script is automatically installed when we run the Adobe Photoshop.
  4. The script is started by selecting the Adobe Photoshop command File > Scripts > EasyDigitalNegatives-v1.

Note. The Easy Digital Negatives script is, of course, tested, but you use it at your own risk. You can get it for free from web site Download page.

Preparation for working with a script

Before we run the program, we need to prepare photographed or scanned files with a grayscale step wedge (see Scanning samples or see Photographing samples ). We may use any of the three grayscale wedges:

  • a basic, made from the negative EasyDigitalNegatives-StepWedge-101-K.tif, which is intended for the production of custom curves
  • a small HSB grayscale step wedge EasyDigitalNegatives-StepWedge-101-HSB.tif or
  • a larger grayscale step wedge EasyDigitalNegatives-StepWedge-256-HSB.tif.

As most operations in the script Easy Digital Negative are done automatically, it is just necessary to crop the photo of the grayscale step wedge to the required dimensions.

  1. In Adobe Photoshop, we open the selected photo of the grayscale step wedge.
  2. We need to crop the photo to the correct size. The simplest way is to use the Crop Tool (1), in which we check the option Perspective (2).

  1. With this tool, we first draw a square around the grayscale step wedge. Then we click on the first corner of sample and move the cropping square exactly to the corners shown on the sample (3). The same operation is performed over the remaining three corners.
  2. Once we select an entire area to cut, the selection is cropped (4).

  1. Now we check for errors in the image that could affect the mapping of tones. In our case of cyanotype, we see that in one square there is a rather bright area that, at the time of calculating the color in the cell, can significantly change its value. We darken this bright patch (5) with the help of the tool Clone Stamp Tool.
  2. Now we can save the sample of the grayscale step wedge.

Note. In the case where the image of the sample is too large or too small, it can be changed with the Image > Image Size command or other commands of your choice.

Correcting mid-tones with mapping

Making adjustments to a sample with mapping (and, of course, with a curve, if you select that option) takes place completely automatically.

  1. In Adobe Photoshop, we open a cropped grayscale step wedge (it is not necessary to convert the image to grayscale mode).
  2. We run the script through the File > Scripts > EasyDigitalNegatives-v1 command.
  3. In the first section, we choose the Mapping option (1).
  4. In the second section, we select the dimension of the grayscale scale wedge. In our example, we have chosen a larger scale with 16 x 16 fields (2).
  5. In the third section, we select the Make gradient map option (3) and then we click on the OK button.

  1. After the program automatically performs normalization and linearization, it will open a dialog box in a few seconds. Here, we select the location to which we wish to save the Gradient Map adjustment.
  2. When the sample with corrections is saved, the program Easy Digital Negativescloses automatically.

Creating curves is exactly the same as mapping, with the difference that in the first section (1) we select the Curves option, in the second we select the size of the grayscale step wedge, and in the third option we select the Make curve operation. Finally, the curve is stored in a folder.

Correction

At the bottom of the working space of EasyDigitalNegatives-v1, we can see an option called Apply correction. If this choice is checked, the script automatically adjusts (2) bigger errors of “posterization” that occur in a poorly made negative (1); this is done during the making of corrections. If you do not want to use the process of mapping, you will still need to manually correct minor errors on curves (see Manual correction of mid-tones ). The second type of correction, which the script executes automatically, is additional linearization of tonal values. Since the results with this option checked are slightly better, the option is selected by default.

Calculating the average correction

For making corrections, three samples or three pictures of the grayscale step wedge are most commonly used, as the average value of the three corrections is much more accurate than the value of a single sample (see The average negative ).

Although we have learned how to manually calculate the average value in the chapter The average negative, we will leave this job in this chapter to the program Easy Digital Negatives.

  1. We run Adobe Photoshop and then the File > Scripts > EasyDigitalNegatives-v1command.
  2. In the window of the script, we select Mapping (1) or Curve (if we wish to calculate an average value of custom curves), and then in the third section we mark the option Calculate map average (2) or Calculate curves average.
  3. After that, the section Add files is shown, where we load at least two or three sample files (i.e. files of type Gradient Map or Adobe Curve) via the Browse button (3).
  4. The average value is calculated in the blink of an eye, so it remains only to save the calculated average correction of the Gradient Map (or curve) through the appropriate dialog box.

Combining corrections

The third operation that can be performed with the Easy Digital Negatives script is to combine the first and second, i.e. the overall and the precise correction into a single file (see Correction of corrections). The advantage of such a combination of layers is obvious. With a single file, we have less work and less chance of error, compared to the case of storing and working with two or more files with corrections.

  1. We run Adobe Photoshop and then the script using the File > Scripts > EasyDigitalNegatives-v1 command.
  2. In the window of the script, we select Mapping (4) or Curve, if we wish to combine two custom curves.
  3. We select Combine 1st and 2nd correction option (5).
  4. After the section Add files is shown, we load two sample files with the applied correction (i.e. files of type Gradient Map or Adobe Curve) via the Browse button (6). In doing so, the order of loading correction is not important because the program automatically detects in which file the second correction is located.
  5. We click on the OK button and save the combined correction.

Making layers for monitor calibration

This method for producing a gradient map layer, with which we make an image on a monitor identical to the printed image, is also very easy.

  1. We open a photo of the developed grayscale step wedge.
  2. The photo must be cropped to the correct size (see Preparation for working with a script).
  3. With the File > Scripts > EasyDigitalNegatives-v1 command, we run the script then we choose the Screen map option in the Method section.
  4. Now we click on the OK button and save the Gradient Map, which will be used for calibration of the monitor (see Calibrating the monitor).

Note. I recommend that you do not perform manual adjustments of files generated by the EasyDigitalNegatives-v1 script, since they probably will not be recognized by the program.