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issue151:tutoriel2

Ceci est une ancienne révision du document !


In this day and age, photography is rife. We all carry around digital cameras integrated into our smartphones that vie with professional grade equipment from a couple of decades ago. Moreover, we can take just about as many shots, and in higher quality, as anybody (other than a professional or an advanced enthusiast) could have done until very recently. We are also rather well-equipped - from a software standpoint - to manage and modify our pictures, altering them for different purposes. However, this situation is not the result of an abrupt change in our photographic habits: I am sure many readers of these columns have a history of taking photos in earlier times, perhaps using rather less capable digital equipment, or even physical films developed using a chemical process. I know I still retain several boxes of such at home, hundreds of paper prints, as well as the cameras that I used to take them. Though they may seem quaint and perhaps better suited to a small museum than to a modern lifestyle, it is no less true that these pictures bring back memories of times gone by, of places and of people - some of whom are no longer in this world. In addition, I also conserve several photos made by other people, related to family circumstances, but at earlier dates. I have absolutely no doubt I am not the only one in this situation.

As may or may not seem logical, I would now like to retrieve some of these documents, and work on them to enhance their technical quality that, in cases, has been sadly let down by what was possible at the time. Some images are faded and yellow from the oxidation of their pigments. Others have creases and dots on them. The earliest are in black-and-white, which is fine from an artistic point of view, but to which I would like to add color to try and capture some essence of the original scenes.

This has been the main source of inspiration for this series, in which I will be going on my internal journey of learning to make something of the old photos in my possession, and others in the public domain due to their age. You, the reader, are welcome to tag along, and I hope to glean some small insight and perhaps an idea or two from time to time. No promises are made as to the quality of the content, or potential errors and omissions. I am a computer scientist, not a true artist or a professional of image restoration. So please take all this as a best effort, but with no firm guarantees - much as is the case of most open-source software. Naturally, being a Linux user, that is what I will be using: open-source applications, on top of an open-source operating system: Linux Mint 19.2 in my case, though there should be no real differences between anything described here and other comparable distributions in the Ubuntu family, or Debian.

A choice of program

Modern distributions of GNU/Linux propose many programs to work on photographs and other forms of digital art. Some applications, such as Inkscape, are oriented towards creating vector graphics, not photos and raster images. Others, such as Darktable, are used to process raw images fresh from a digital camera, for management, and to quickly apply effects and enhancements to the complete image. And then, there are the many general-purpose applications with a wide range of effects and tools for editing complete images, but also drawing and modifying local details. Perhaps the best-known of these is the GNU Image Manipulation Program (GIMP), often installed within a distribution’s default selection of software. A good stand-in for Adobe’s commercial Photoshop, it can certainly be used for our purposes and to good effect.

However, for this series I have preferred to focus on a different program, Krita, that is perhaps slightly less well-known to the general community outside of people involved in visual art, being more focused towards artistic drawing than GIMP. It came to my attention when researching software to use with the recent acquisition, a digital tablet, with which it integrates very nicely.

Krita is based on the Qt widget set, and thus often associated with the KDE Plasma desktop. But, as with most modern applications, it does integrate rather well with other desktop managers such as Gnome or Cinnamon, and, in fact, I tend to use it with a fairly standard Linux Mint. Other options include using Krita under Mac OS, or Windows. Further information may be found on the project’s home page, at https://krita.org/en/. As usual with Ubuntu and its derivatives, installation is usually a matter of using terminal commands:

sudo apt update ; sudo apt install krita

Krita should also be easily available in graphical software managers, though I cannot say I have tried out that route.

Acquiring the images

Before working on any specific images, they must, at some point, be converted to a format compatible with computers. Pictures taken with digital cameras may be stored on hard drives, or even USB-connected pen-drives. These formats will usually give no problem, as long as some means of connection is available. The situation may become more complex with the CD-ROMs that many camera-film developers provided alongside paper copies in the final years of chemical film usage - since most modern computers lack an optical drive. An older laptop may be of use, though I would advise a liberal application of compressed air to clean some of the accumulated dust out before putting such bask in use reading CDs. An external CD reader connected to our main computer via USB may be a better alternative; these are not expensive and may be stored for other purposes.

Some time ago, flatbed scanners were a widely-used peripheral to convert physical documents to digital form. I still have one on a shelf somewhere, which I could plug in and use in conjunction with the Simple Scan software that comes with Ubuntu these days. However, I will not be using it to convert paper prints to digital form for the following reason. My desktop scanner, like most, has a resolution of 300 dpi (dots per inch). When applied to a standard paper print of about 4 by 6 inches, or 10 by 15 cm, this gives a digital file with resolution 1200 x 1800 pixels. But my cheap Samsung phone has a camera with a resolution that goes up to 4128 x 3096 pixels (13 Megapixels). So one can achieve both better resolution and an easier workflow to transfer the images to a computer by simply taping the prints to a vertical wall in a well-illuminated place, and taking a picture of them with the mobile phone’s camera. This is the miracle of technology ever moving forward. Just make sure to take the photos from a point as squarely in front of the original as possible, and do not let shadows or the use of a flash mar the result.

Series outline

In the next part of this series, we will commence work on a simple landscape, a photo of the castle of Foix in southern France about the turn of the century. With the passage of time, this photo is now slated to fall within the public domain. It has already been digitized by the Rosalis project of the municipal public library of Toulouse, and may be downloaded from Wikicommons at address: https://commons.m.wikimedia.org/wiki/File:Ch%C3%A2teau_en_ruines_(8056081904).jpg .

Interested viewers may wish to download this image, explore its various technical difficulties as a restoration project, and perhaps play around a little before the next episode. Until then, take care!

issue151/tutoriel2.1575118185.txt.gz · Dernière modification : 2019/11/30 13:49 de auntiee