Paperback: 112 pages
Publisher: CreateSpace Independent Publishing
1 edition: June 21, 2014
Product Dimensions: 8 x 0.3 x 10 inches
(20,3 x 0,7 x 25,4 cm)
Celluloid films and negatives have been used in a wide variety of work areas, from industry (e.g., screen printing, offset printing, fabrication of printed circuit boards, etc…) to art (e.g., graphics, photographic printing techniques, etc…), and have been almost entirely replaced by digital negatives. This is due to the fact that the processing and manufacture of digital negatives is faster, cheaper and, finally, simpler. In recent years, celluloid films are hardly in use anymore.
In this book, we will focus on digital negatives which are needed in order to produce photos with the help of old photographic techniques.
As in the other books from this series, in this volume we will deal more with practical examples than with theory.
First we will learn the basic concepts and procedures for making digital negatives: how to set up a program (in our case we will use Adobe Photoshop); we will talk about the basic and somewhat more complex printer settings; we will learn how to scan and photograph test samples; and, of course, we will discover how to determine the standard printing time, in other words how to achieve maximum dark color of selected photographic emulsions and how to get the brightest color, etc..
The second part of the book explains how to create negatives with the help of the most well-known process using custom curves, which is followed by a description of a new method of mapping tones; I have developed this method due to dissatisfaction with the quality of the first one.
Towards the end of the book, instructions for simple calibration of the computer screen are presented (this makes the photo on the screen identical to the printed photo), and there is a presentation of a free script for Adobe Photoshop which can automatically carry out the procedures presented in this volume; of course, just in case, you will learn the full procedures, as described on the following pages.
Since the production of digital negatives consists of a large number of quite different tasks, in this chapter we will first present the global workflow.
Before we start to work, we need to know some basic concepts about contemporary photography. We will learn the meanings of color space, gamma, and 8- and 16-bit images.
Before the production and processing of digital negatives, we must change some of the program settings, in our case the settings in Adobe Photoshop. The most important item is the choice of the working space Adobe RGB (1988).
In this step, we choose the option Printer Manages Colors, with which we can change the print density. In this way we can print the most demanding negatives, even with a cheaper printer.
For the precise manufacture of digital negatives, we need to know the optimal way to reproduce the grayscale step wedge, from which we will make corrections. Samples can be digitized by means of a camera or a scanner.
In this way, treated samples will be further used for the correct display of photographs on the computer screen.
The basic parameter for printing photos is the so-called standard printing time. This is the time it takes for the darkest color to be achieved on the photo, which can be displayed by selected photographic sensitizer.
The most suitable color for printing negatives is also called the optimal light blocker. This is most often used to print the brightest tones in the photo.
We can use different procedures to find the optimal blocker. One of the simplest methods is to use a negative with color patches which are printed with different print densities.
Slightly more demanding readers can use a more accurate table with different color values instead of the searching technique.
Once we have learned how to print the darkest and brightest tones in the photo, we can print the negative with the help of the most appropriate color or blocker. A photo or a test sample is most often inverted to the negative, mirrored, and printed with the color that correctly blocks the UV light.
The next step for producing accurate digital negatives is the normalization of the photo. This is essentially the expansion of the tonal values in the photo, in a way that is adapted to normal human vision.
When the tonal values of the photo are “stretched out” by normalization, we must also properly distribute the mid-tones of the photograph. This is carried out by a so-called linearization.
The most popular method is to produce custom curves, but in this book we will focus on the mapping method, which eliminates some of the errors that occur when working with curves.
If we want to make a correction that is as accurate as possible, we print at least three samples of the grayscale step wedge using the same negative. In the historical and alternative techniques, each photo is slightly different from the previous one, mainly because of manual coating of the sensitizer. Of course, the most ideal correction will be closer to perfection if we make the greatest possible number of samples, from which the average value of the correction is then calculated.
Many users are satisfied with the appearance of the first correction (the curve or the gradient map), but slightly more demanding users often check for corrections that can further improve the look of a photo. In this case, we first print the previously corrected negative, normalize it, perform linearization, and, of course, print the photo with both corrections applied.
The result is often a slightly better correction, but sometimes somewhat worse.
Calibration of the computer screen before manipulating a digital photo is an especially necessary process by which black-and-white photographs are shown in the colors of the selected photographic techniques on the computer screen. Such a colored preview allows much more precise image manipulation.
Making photographs using digital negatives is the final step in the production of digital negatives. Only when we have determined the standard exposure time and the correct light blocker, performed normalization and linearization, applied corrections, and changed the appearance of the photo on a calibrated screen, can the photo be printed.
The script Easy Digital Negatives is a computer program that runs in Adobe Photoshop CS3 and above. It is extremely fast and can automatically make adjustments, calculate average corrections, combine more corrections, and calibrate the screen, etc… In short, if you stick to the rules described in this book, you’ll soon realize that the script can help you create a digital negative in just a few minutes.
But now it’s time to start with a description of the basic concepts that you need to know.
For the production of photos through most of the old photographic techniques, we need a negative which is most often an inverted image of the photo that is to be printed. Exposure of the photograph is conducted so that the negative (1) is placed on a light-sensitive image carrier, for example on paper (2), then is exposed in a frame by means of solar or UV-light (3). The carrier is then developed (4) and often fixed (5).
But this seemingly simple process can become quite complicated when we discover that the various photographic processes or chemicals which are used to make a photographic sensitizer react differently to an UV light. For example, when using the same, untreated negative (6), we expose it first as cyanotype and then with salted paper coated with silver nitrate, we get two visually very different results. The photo of a cyanotype becomes contrasted with almost no intermediate grays (7), while the photo on salted paper becomes quite dark. On the latter, we lose all bright tones (8). An untreated negative in our case, therefore, does not correspond to any of mentioned photographic processes.
If we want to print a selected photo in such a way that it will have the same tonal values as an original photo (10 and 12), we need a different negative for cyanotype (9) and another for salted paper (11). How to make a photo from negative, having identical tonal values as the original photo is explained in this book.
The old masters resolved the problem of different reactions of light-sensitive emulsion to light in two ways. Firstly, they changed the contrast by using different chemical compositions of sensitizer on the positive; for example, to silver nitrate they added potassium dichromate, and in platinotype, potassium chlorate was used, etc… The second method required changing the negative through in-camera exposure and various methods of development of the negative.
Today, these old techniques are used by only a few photographers, as, given our appreciation of time, they are quite slow and ineffective. We can compare the old masters’ techniques with today’s perspective: in the old days, processing a photo, darkening and lightening it, retouching, and changing its tonal values were done with great difficulty; now, we can do the same tasks without any problem in just a few minutes with the help of computers.
A second major problem in today’s digital world is represented by the old materials, which are available only in limited quantities. A huge number of different films, developers, toners and other chemicals which were sold until the end of the twentieth century are now limited to only a few hundred products, which are found most often only after a long search. But people will always find a solution. The old photographic techniques were revived with the use of new materials, which are much more efficient, but produce the same high-quality result.
The process of making digital negatives is easy, but in some cases, if we are obsessed with perfect technological control, it can become quite complicated. In this book, we will of course limit ourselves to the optimum solutions that are effective, affordable to everyone, and at the same time of quite good quality.
A digital negative can be modified with the help of digital image processing programs; in our case, we will use Adobe Photoshop.
For making the digital negatives which are described in this book, we need: a PC, a program for digital photo processing, a printer, a scanner or camera, and, of course, some transparent film.
For making digital negatives we need a personal computer, in which a program for digital processing of photos and a program to capture photos from a camera or scanner are loaded. Of course, it is better if we use a high-quality PC with a good monitor, but a very good digital negative can also be produced with hardware of average quality.
The program which is used for processing digital photos should be of slightly better quality. The most widely used programs are Adobe Photoshop and the free program GIMP (The GNU Image Manipulation Program). The first is found on the website of Adobe and the other is at the web address www.gimp.org. In this book, we will use Adobe Photoshop CS version 4, but all of the described commands can also be executed in the same way in other versions of the software.
The printer is crucial for printing digital negatives. In most cases, inkjet printers are used, since their prints, for our purposes, are significantly better than prints of laser printers. In the example shown below, we see that on the transparent film which was printed on a laser printer, areas of highly visible black spots appear brightly (1). This is normal for a “laser” picture, while an inkjet printer works in a completely different way. Selected color is composed of different colors, which uniformly fills the surface of the paper (2). Of course, the print quality once again depends on the price of the printer and that of the ink. The more expensive the printer and ink are, the more high-quality print we get.
For making negatives, we will need a device to read the color values of a developed sample. We can use a scanner or digital camera of slightly better quality. Similarly to all other devices, these are also subject to the rule that a better scanner, and of course more expensive scanners, give better results. One of the few conditions demanded from a scanner is that it allows manual setting of the parameters of the scan. Thus, the results are independent of any automatic settings.
The developed test samples which are printed with a digital negative can also be converted to digital form by photographing them with a camera. The quality of the image again depends on the quality of the camera and on compliance with the basic rules of photography. This will be described in Photographing samples.
The digital negative can be made from plain paper, from tracing paper (which was once used by technical draughtsman), or from overhead transparencies or transparent films that are designed for offset, silk or “alternative” prints. Among these materials, there are, of course, quite big differences.
The range of tones printed with a plain paper negative (3) is very small, so the very light and the darkest tones are hardly visible. Negatives printed on tracing paper give a slightly better tonal value, but the image is rather blurry because of the greasiness of the paper (4). Much better negatives are those which are printed on overhead transparencies (5). Here, we will notice significantly greater tonal values. But the very best are negatives printed on transparent films for offset printing and “alternative” photography (6).
Transparent films for “alternative” photography or offset printing are, of course, much more expensive than the other films. However, they allow us high-precision printing due to their special coating, which is capable of absorbing much more color from the ink jet printer. This, in turn, allows us to print negatives with much more contrast.
In this book, we will use only transparent film, since they produce much better results than other media.
The transparency of materials and printed colors can be checked in a very simple way. A blank document is opened on the computer screen to show a completely white surface. On the screen, the various pieces of negatives are then placed side by side (7).
Note. Sometimes, when using some of the more expensive transparent films to print a colorized negative, bright bands will appear on a developed photo. In this case, we need to change the brand of transparent film or we have to print the negative with black color in RGB mode.
For making digital negatives we will need some files. For a quick search for a blocker (or color on the negative that best blocks the UV light), we will need the file Blockers.tif (1).
Then we need a so-called grayscale step wedge, i.e. a black-and-white picture which is made of squares with different levels of brightness.
When working with curves, we use a grayscale step wedge in which colors are numbered with shades of black. The white color in the file EasyDigitalNegatives-StepWedge-101-K.tif is tagged as 0% black, and black is marked as 100% black (2).
For mapping, calibration of the screen, and all other procedures, we use the grayscale step wedge in which the tonal values are presented with the HSB color model. In this model, the white color is represented as 100% bright and black as 0% bright. The name of this file is EasyDigitalNegatives-StepWedge-101-HSB.tif (3).
Although the majority of users prefer using gray wedges with 101 color values, I frequently work with a grayscale step wedge with 256 colors (4). This method is able to display 2.5 times more color values, which of course allows a more accurate production of negatives.
The sample of this larger grayscale step wedge is saved in the file EasyDigitalNegatives-StepWedge-256-HSB.tif.
In the section, which is intended for slightly more demanding users, we will try to find the most accurate blocker of UV light on a negative with the help of file HSB_Grid.tif.
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.
Note.The last chapter of this book can be found on the webpage Easy Digital Negatives.