Easy Digital Negatives (EDN) ColorBlocker is a free scripting application that complements Easy Digital Negatives. In most cases, we do not need the EDN ColorBlocker application. Still, when the selected photographic technique (Gum Print, Carbon print, Oil Print,…) cannot show more shades, it becomes almost mandatory to use ColorBlocker.

In photographic techniques with a limited range of color shades, we can increase the range by using a table of 256 tones1. Still, in most cases, we get even better results by printing the negative with the correct color instead of the black&white color. Black and white negatives are not always the best for taking photos with old photographic techniques.

Another advantage of using a color negative is visible in the better dynamic range of a printed photo. If we use only one black color for printing, the negative is printed with about 100 possible shades, combined with software adjustments of intermediate tones. But ONE color printed with the printer most often consists of four or more primary colors: cyan, yellow, magenta, and black (for example HSB 330-100-30 is CMYK 48-93-57-62). A cheaper printer will, therefore, have 3 more color shades available for printing, resulting in a few million color combinations. So, we can use the full-color spectrum of the printer when printing color negatives. When using printers of six or nine colors, of course, the print quality is much higher. And there is no need to buy special programs, or extra shades of custom black color.

System requirements

EDN ColorBlocker is the same as Easy Digital Negatives scripting software executed from any web browser. We can run the program from the web or download it to our home computer. Therefore, EDN ColorBlocker works on all operating systems, including tablets and smartphones, if desired. We can use the results of the EDN ColorBlocker script in most photo editing programs, such as GIMP, Affinity Photo, Adobe Photoshop, Lightroom, etc. Using this solution, we can print a beautiful negative on any printing device, on all types of printers, on all models, even the cheapest. We can use a camera or any desktop scanner to read the results.

Program Description

We use the program by first printing the EDN_HSB2.tif file on a transparent digital negative. Then we create a positive image. We can photograph or scan this positive sample. We crop it and upload the sample into the EDN ColorBlocker script. The results are calculated instantly.

In the upper half of the program, we see results for the so-called Optimal and Maximum color blockers. We use these results when we want to produce a negative manually, with any desired procedure. In the lower half of the program, there are files with the results of the Optimal and Maximal blocker. We insert these files into a program where we process negatives. See Adding EDN Gradient Map to Adobe Photoshop, Adding EDN LUTs to Adobe Photoshop, Adding EDN Gradient Map to GIMP, Adding EDN LUT to Affinity Photo, and Adding EDN LUT to Adobe Lightroom.

MAXIMUM BLOCKER – If we want to print a photo in very dark tones, we can extend the exposure time. But in this case, we can lose white tones. Already the very first photographers found that red color, for example, blocks UV light much better than black or blue. And EDN ColorBlocker is even more sophisticated. EDN ColorBlocker calculates the Maximal blocker or color that most strongly blocks UV light, for any photographic process, using any printer and any transparent film.

OPTIMAL BLOCKER – When using some old photographic techniques, we notice that there are only a few shades of black available to produce transparent digital negatives. I mentioned earlier1 that I solved this problem by replacing the gray 101 grayscale wedges with a 256 grayscale wedge. However, since this was not enough to produce perfect results, I started looking for the color that would expand the range of tones. I named this color the Optimal Blocker. It is a color that does not block the most strong UV light. Still, it is a color that can display the most extensive color range on a transparent film or in the desired photographic technique.

How Does the Program Work?

During operation, the program first removes all the colors that create “posterization” or inversion of tones. Then it looks for some colors with the highest tonal ranges. Among these colors, the program chooses the colors with the most evenly distributed, or with the smallest so-called standard deviation of shades.

EDN ColorBlocker version 3.0 is further improved. Instead of adding color using Screen and Colorize modes, I’m in this version searching for the darkest, the lightest, and the color of the ideal mid-tone. The result, instead of the original 15 useful tones, now allows the use of almost all available shades. The negative curve is now almost linear, and the number of available colors increases virtually across all the spectrum of printer capabilities.

These results are stored in a file that can then be inserted into any photo editor with a few clicks. The terrible negative is thus with the help of EDN ColorBlocker instantly transformed into a slightly contrasting, but almost correctly displayed, image.


The workflow described in this section is rather short, but more details are presented in the Video / ColorBlocker menu. If anyone wants to know more details, such as setting up a printer, selecting the exposure time, etc., they can find it in the Easy Digital Negatives book, available from all Amazon stores.

  1. Download the EDN_HSB2.tif file from the Downloads page.
  2. Image with the HSB table should not be inverted or mirrored, but only printed on transparent film or paper.
  3. With the selected photographic process, we create a positive image of the HSB table.
  4. The HSB table is photographed or scanned in color mode at a resolution of 300 pixels.
  5. We crop the image to the appropriate size. The procedures depend on the chosen program (see also Cropping EDN samples in Photoshop, Cropping EDN samples in Affinity Photo and Cropping EDN samples in GIMP).
  6. We open the file in EDN ColorBlocker, which calculates blocking colors in a few milliseconds.
  7. The program displays Maximal and Optimal blocker color. Below are links to the files. The first file of the cube type is the so-called LUT file that we can use in Adobe Photoshop, Lightroom, Affinity Photo, and more. The second file is a Gradient map that we employ in Adobe Photoshop, and the third is a Gradient map used in GIMP. To save files, click on them.
  8. In most cases, we use only the files of the Optimal blocker.
  9. We color the negative with the selected file by first processing the image, then inverting and mirroring it, and then finally coloring it with the selected file.

The workflow is also shown in the videos on the Videos/ColorBlocker page.

  1. When I was improving the system for the production of transparent digital negatives years ago, instead of the “standard” 101 grayscale wedges, I “invented” the 256 grayscale wedge table. In doing so, I have found that grayscale wedges with even more fields are inefficient. With the increase in the number of patches, there is a growing inaccuracy in reading the data. Therefore, if you find that results are getting worse for photographic techniques with extremely high shades, use a 101 grayscale wedge instead of a grayscale wedge with 256 squares.