issue153:krita
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Ci-dessous, les différences entre deux révisions de la page.
Prochaine révision | Révision précédenteProchaine révisionLes deux révisions suivantes | ||
issue153:krita [2020/02/01 17:26] – créée d52fr | issue153:krita [2020/02/11 09:23] – d52fr | ||
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- | This series is aimed at 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, glean some small insight and perhaps an idea or two from time to time. No promises are made as to 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. | + | **This series is aimed at 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, glean some small insight and perhaps an idea or two from time to time. No promises are made as to 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. |
- | In this part of this series, we will continue work on a simple landscape, a photo of the castle of Foix in southern France. With the passage of time, this photo is now stated to fall within the public domain, has already been digitized by the Rosalis project of the municipal public library of Toulouse, and may be downloaded from Wikicommons at address: https:// | + | In this part of this series, we will continue work on a simple landscape, a photo of the castle of Foix in southern France. With the passage of time, this photo is now stated to fall within the public domain, has already been digitized by the Rosalis project of the municipal public library of Toulouse, and may be downloaded from Wikicommons at address: https:// |
- | In the previous episode, we cropped the image slightly to remove some damage along the lower and left edges, used the airbrush to clean up more damage near the top edge and some typical dark spots that were quite apparent on the clear sky, and then an overlay layer along with a dark color and the airbrush to reduce the effect of a large whitish blemish in the lower left corner. | + | Cette série a pour but d' |
- | This time, we will try to solve the issue of the dark castle and trees to the right of the photo, | + | Dans cette partie de la série, nous commencerons notre travail sur un simple paysage, une photo du château de Foix dans le sud de la France, au début du 20e siècle. Avec le temps, cette photo est tombée dans le domaine public, elle a été numérisée par le projet Rosalis de la bibliothèque municipale de Toulouse et peut être téléchargée à partir de Wikicommons à l' |
- | It is always instructive to take a quick histogram of our layer. With our only layer active, choose menu option “Layer”, | + | **In the previous episode, we cropped the image slightly |
- | In this plot, the amount of pixels in each color is plotted, with frequencies | + | This time, we will try to solve the issue of the dark castle and trees to the right of the photo, and put some color back into the scene. Before proceeding, we will make a copy of the Krita file, to save the current state for future reference or as a means of recuperation if disaster strikes. In our new copy, we will take the opportunity to combine all three layers present (the original |
- | In other words, the darker part of our image --the landscape itself-- is quite well-balanced, with pixels of many shades of gray. However, sky colors are very far apart from the earth, with a clear separation of a region of lighter colors in which there are not very many details. This results in a high level of contrast. For a more pleasing result to the eye, an ideal situation would be that in which the histogram plot would be as flat as possible, with a wide range of color values giving a richness of details. | + | Dans l' |
- | Moving forward, we have one basic choice to make. Do we leave the sky as it is, in sharp contrast to the ground, or do we try to compress sky colors into a narrower band, thus freeing up some color space that we can use to spread out earth colors somewhat. In our case, our sky is already quite washed out with little detail left in our original photo, so I feel that by compressing it further into even fewer colors we are actually losing very little detail. | + | Cette fois-ci, nous essaierons de résoudre le problème de noirceur du château et des arbres à droite de la photo et de redonner quelques couleurs à la scène. Avant de procéder, nous ferons une copie du fichier Krita, pour sauvegarder l' |
- | To alter the color balance of a layer in Krita, go the menu option “Filter”, then “Adjust”, then choose --for instance-- “Color adjustment curves”. As can be seen in this submenu, | + | **It is always instructive to take a quick histogram of our layer. With our only layer active, choose |
- | In the curves’ dialog, the diagram | + | In this plot, the amount of pixels |
- | The curve itself is initially a diagonal line. This means that, at first, each current color will be transformed into itself — i.e., it will be left as it is. Now, by simply moving the curve (and so introducing control points represented by dots), we will tell the application which alterations to perform. Moving the curve upwards will make the affected range of colors lighter, and moving it downwards will darken them. In our case, the general intent was to lighten the earth, so I raised the curve lightly. It is best to avoid wide, sweeping movements: regions where the curve approached being either completely vertical or completely horizontal tend to give rather strange results that shock the eye. Please note, also, that I have retained a second control point low in the left corner: this is here to ensure that pixels that are completely black remain so. | + | C4est toujours instructif de prendre un rapide histogramme de notre calque. Notre unique calque étant actif, choisissez l' |
- | Our resulting picture, so far is: | + | Dans ce graphe, la quantité de pixels pour chaque couleur est tracée, avec les fréquences des couleurs sombres à gauche et des couleurs claires à droite. Pour notre image, nous pouvons observer un pic aigu à droite, ce qui correspond à la grande quantité de pixels lumineux de notre ciel, qui couvre un tiers de la surface totale de l' |
- | If we consult our new histogram, we can see that the main image has colors spread out over a wide range, while the sky is still bunched up in a single sharp peak to the right. This last bit does not represent | + | **In other words, the darker part of our image --the landscape itself-- |
- | So far, our photo has progressed quite a bit in quality in comparison to the original. However, one aspect is lacking to give the scene a tad more realism: colors. These were lost during the initial photography, | + | Moving forward, we have one basic choice to make. Do we leave the sky as it is, in sharp contrast to the ground, or do we try to compress sky colors into a narrower band, thus freeing up some color space that we can use to spread out earth colors somewhat. In our case, our sky is already quite washed out with little detail left in our original photo, so I feel that by compressing it further into even fewer colors we are actually losing very little detail.** |
+ | |||
+ | En d' | ||
+ | |||
+ | Pour continuer, nous avons un choix de base à faire. Laissons-nous le ciel tel qu'il est, avec un contraste prononcé par rapport au sol, ou est-ce que nous essayons de compresser es couleurs du ciel dans une bande plus étroite, libérant ainsi un peu d' | ||
+ | |||
+ | **To alter the color balance of a layer in Krita, go the menu option “Filter”, | ||
+ | |||
+ | In the curves’ dialog, the diagram in the middle represents the transformation we will apply to colors. The horizontal scale represents current colors, and the vertical the colors into which they will be transformed.** | ||
+ | |||
+ | Pour modifier l' | ||
+ | |||
+ | Dans le dialogue des courbes, Le diagramme du milieu représente la transformation que nous appliquerons aux couleurs. L' | ||
+ | |||
+ | **The curve itself is initially a diagonal line. This means that, at first, each current color will be transformed into itself — i.e., it will be left as it is. Now, by simply moving the curve (and so introducing control points represented by dots), we will tell the application which alterations to perform. Moving the curve upwards will make the affected range of colors lighter, and moving it downwards will darken them. In our case, the general intent was to lighten the earth, so I raised the curve lightly. It is best to avoid wide, sweeping movements: regions where the curve approached being either completely vertical or completely horizontal tend to give rather strange results that shock the eye. Please note, also, that I have retained a second control point low in the left corner: this is here to ensure that pixels that are completely black remain so. ** | ||
+ | |||
+ | La courbe est-même est initialement une diagonale. Ça signifie que, d' | ||
+ | |||
+ | **Our resulting picture, so far is: | ||
+ | |||
+ | If we consult our new histogram, we can see that the main image has colors spread out over a wide range, while the sky is still bunched up in a single sharp peak to the right. This last bit does not represent a major alteration over the original state, while the main body of the image is more balanced than previously. ** | ||
+ | |||
+ | Au point où nous en sommes, notre image résultante : | ||
+ | |||
+ | Si nous consultons notre nouvel histogramme, | ||
+ | |||
+ | **So far, our photo has progressed quite a bit in quality in comparison to the original. However, one aspect is lacking to give the scene a tad more realism: colors. These were lost during the initial photography, | ||
+ | |||
+ | Jusqu' | ||
+ | |||
+ | **Our takeaway here, is that in order to colorize our image, we will need to add back the information that has been lost. Luckily, our experience as humans tells us that the sky should probably be blue, and the trees green. | ||
+ | |||
+ | To finish up for today, let us add in Krita a new transparent layer. We will also need to convert the image from gray-scale to color. To do so, choose menu option “Image”, | ||
+ | |||
+ | Notre conclusion ici, c'est que pour coloriser notre image, nous aurons besoin de lui redonner les informations qui ont été perdues. Heureusement, | ||
+ | |||
+ | Pour terminer aujourd' | ||
+ | |||
+ | **Now, with the airbrush at a low opacity setting (about 0.2 should give good results), and rather broad opening (perhaps in the range of 40 to 300 pixels, depending on overall image size), let us brush in some color. Unlike in the first part of this series, when we were covering up small defects, now we will need to proceed with wide open strokes giving coverage to large areas at once, but with little density. For our first attempt, we will be using just three colors --a light blue, a darker green, and a reddish brick pink-- and not worrying about complete coverage of each part of the scene.** | ||
+ | |||
+ | Maintenant, avec l' | ||
+ | |||
+ | **The result, so far, is quite reminiscent of period hand-coloring of black and white photographs in the early 1900s. We already get a better appreciation of how the city’s rooftops and white buildings must have stood out from the surrounding vegetation and blue sky. However, we can also see that this approach has some drawbacks. The main one is that, since we are simply adding color on top of an existing black motive, we are darkening considerably the scene as a whole. This is not very realistic. Another problem is that our green coverage, for example, is uniform across different types of trees and grass, each of which would have had its very own shade and intensity. So, we need to think about how to modulate our new colors as a function of what they are laid out upon. This is what we shall do in the next episode of our series, though the reader is encouraged to experiment freely on his/her own beforehand. Until then, take care!** | ||
+ | |||
+ | Le résultat, ici, rappelle asez bien la période où on colorisait les photographies en noir et blanc, au début des années 1900. Nous obtenons déjà une meilleure appréhension d'à quoi ressemblaient les toits de la ville et les immeubles blancs devaient avoir poussé au milieu de la végétation et sous le ciel bleu. Cependant, nous pouvons voir que cette approche a des inconvénients. Le principal est que, depuis que nous ajoutons de la couleur par dessus les motifs noirs existants, nous assombrissons considérablement toute la scéne. Ce n'est pas très réaliste. Autre problème : notre couverture en vert, par exemple, est uniforme pour différents types d' | ||
- | Our takeaway here, is that in order to colorize our image, we will need to add back the information that has been lost. Luckily, our experience as humans tells us that the sky should probably be blue, and the trees green. | ||
- | To finish up for today, let us add in Krita a new transparent layer. We will also need to convert the image from gray-scale to color. To do so, choose menu option “Image”, | ||
- | Now, with the airbrush at a low opacity setting (about 0.2 should give good results), and rather broad opening (perhaps in the range of 40 to 300 pixels, depending on overall image size), let us brush in some color. Unlike in the first part of this series, when we were covering up small defects, now we will need to proceed with wide open strokes giving coverage to large areas at once, but with little density. For our first attempt, we will be using just three colors --a light blue, a darker green, and a reddish brick pink-- and not worrying about complete coverage of each part of the scene. | ||
- | The result, so far, is quite reminiscent of period hand-coloring of black and white photographs in the early 1900s. We already get a better appreciation of how the city’s rooftops and white buildings must have stood out from the surrounding vegetation and blue sky. However, we can also see that this approach has some drawbacks. The main one is that, since we are simply adding color on top of an existing black motive, we are darkening considerably the scene as a whole. This is not very realistic. Another problem is that our green coverage, for example, is uniform across different types of trees and grass, each of which would have had its very own shade and intensity. So, we need to think about how to modulate our new colors as a function of what they are laid out upon. This is what we shall do in the next episode of our series, though the reader is encouraged to experiment freely on his/her own beforehand. Until then, take care! | ||
issue153/krita.txt · Dernière modification : 2020/02/12 14:44 de auntiee