Even if you possess own staff of photographers-professionals and can receive for operation of the image of ideal quality, to you, at least sometimes, it is necessary to deal with originals from the most different sources. It is a question of photos from collections on CDs-disks, images from old printing issuings, репортажных photos and so forth Collections, especially Kodak manufactures, as a rule, contain unduly dark images. Old photographic materials from time fade, on them mandatory there are defects (scratches, stains). The amateur photos made cheap devices, very often have "wrong" colors. But if the original content interesting and expressively is more useless to the present creator to be afraid of difficulties. By means of Photoshop you can lead even not very qualitative image to a professional type. Certainly, there are restrictions, and it is impossible to hope that the photo from the newspaper of fifty years' prescription can be corrected to level of studio shooting. However possibilities Photoshop in respect of improving of a type of images are very wide. If the original already has high quality, the program allows to make its simply ideal.

Why one picture seems to full to life, and another — plane as desktop, with indiscernible details? The answer is obvious to the photographer — for the best image quality it, at first, should have an optimal range светов and shades that does objects of shooting by more relief, eliminates an unpleasant gray shade. Secondly, for enrichment of a picture by details the contrast magnification in that pitch interval, where their greatest quantity is required. These two positions are absolutely valid and for image handling in program Photoshop.

From the point of view of Photoshop tone of the image are characterized by brightness пикселов with fixed values from 0 to 255. That part of the full range of brightness which is used in the image, carries a title of a pitch range of the image. The more widely the pitch range, the "more deeply" color and is better study of details. This task is solved by correction светов and shades. In an ideal in the image all values of brightness (tone) should be used.

If to break all pitch range into three unequal parts, that the dark part will be called shades, the most light — light, and will in between be allocated the big interval of average tones. Сюжетно the important fragment of the image can be in any of these parts where there should be a maximum quantity of shades. Correction of tones consists in contrast magnification сюжетно an important pitch range.

The press badly plays back very dark and very light tone. The eye too is arranged so that is better areas of average brightness are perceived. Therefore in concept of correction include also offset сюжетно an important pitch range towards average tones if the most necessary details are far in светах or in shades.

At fading of photos, wrong scanning, violation of conditions of shooting and in other cases dim images can turn out. A common example — the document Bmw.jpg from the worker of a diskette (fig. 8.1). In real life the new, polished machine pleases an eye with dazzling flares on the case and dark, almost black shades on buses. On the same image is not present either white, or black — flares light gray, shades dark gray. As a result the composition seems covered rather dirty дымкой and, of course, "does not pull" on the board.

In total in the numeral 8-bit image of 256 gradation of brightness — from black (brightness 0) to white (brightness 255), and пикселы can be arranged on gradation nonuniformly. For example, if in the image it is a lot of пикселов with brightness 100—150, it means looks an average on brightness. In the dark image it is a lot of пикселов with small brightness, in light — with high. Photoshop is able to build allocation schedules пикселов on brightness — histograms. Looking at the image histogram, you see at once, what interval of brightness is not involved in it and, proceeding from this data, can select a correction method. In following exercises we work with a pitch range of various images on brightness.

1. Open the document Bnw.jpg. Select command Histogram (Histogram) of menu Image (Image) (fig. 8.2). On axis Х pitch gradation, or levels (levels), in a range from 0 to 255, and on a y axis — an amount пикселов each level are allocated. In the given image it is a lot of пикселов average tones also miss пикселы in светах and shades.

For correction of lacks of this image we use window Levels (Levels). The principle of similar correction is simple: as in edge ranges is not present (or very little) пикселов, means, details of appropriate brightness on the image miss. You appropriate the most dark existing пикселам images zero brightness, and the most light — maximum. Then tone of the image are expanded on the full range of brightness. The given operation name the extension of a pitch range.

1. Select command Levels (Levels) submenu Adjust (Correction) of menu Image (Image). Dialog box Levels (Levels) contains the image histogram (fig. 8.3,). Black and white slider on the histogram show input levels black and white. Numerically these levels are displayed in the data entry fields marked in a picture with mugs. At window discovery the black slider is installed at brightness level About, and white — at level 255.

2. Move a white slider on value 235. The image became noticeable more brightly and more contrastly (fig. 8.3,). The program appropriated the maximum brightness all пикселам which brightness was at window discovery (on an input) more than 235. Remaining brightness levels were reallocated accordingly.

3. Drifting a black slider on value 35, you appropriate minimum, zero brightness all пикселам with brightness less than 35. What happens at cutting off of edge brightness? The remained levels uniformly are arranged on all range. As now it is less than brightness levels, at a stretching dips are formed, i.e. some levels of brightness simply are not present. Push the button APPRX.

4. Again open window Levels (Levels) for the modified image. On the histogram dips of brightness levels are well visible. As it is not enough these dips, they are imperceptible neither on the screen, nor on the press. Note that input levels светов and shades are again installed on zero marks.

5. If you strongly expand a range of tones reduction of an amount of halftones becomes noticeable. Install in window Levels (Levels) input level black on 60, and white — on 170. The image became similar to the poster. This defect name sometimes pasteurization (from English poster — the poster).

6. For a canceling set in window Levels (Levels) of parameters without window closing push ALT key. Button Cancel to (Cancel) turns to button Reset to (Recover). Click on it. Offset of levels - is cancelled, but the window remains opened, and it is possible to begin correction again.

7. For closing of a dialog box without correction performance click on button Cancel to (Cancel).

Other very widespread defect of images — too big or too small exposure. In the first case the image turns out very light, in the second — too dark. Correction of such images consists in gamma change — average tones of the image (the gamma is measured in standard units from 0 to 10). You shift tone averages aside большей or smaller brightness. Thus the pitch range remains former.

1. Open the document Interior.jpg (fig. 8.4,). Apparently from its histogram (fig. 8.4,), details are on all interval of brightness, therefore cutting off of levels leads to loss деталировки in светах. However the histogram peak is in deep shades, and the image benefits, if becomes a little more light. We use the histogram windows Levels (Levels) for correction of gamma of the image.

2. Open window Levels (Levels). Gray »a slider (fig. 8.5, shows position of average tones, i.e. gamma of the document. The gamma at the moment of window discovery is equal to unit that group Input Levels data entry field (Input levels) is displayed on the average.

3. Drift a gray slider towards shades. The gamma increases. »The image becomes more light (fig. 8.5. Note that shades and bright light remain invariable.

4. Save a state picture.

What happens at gamma change? Drifting a gray slider, you expand one part of the histogram at the expense of another. In this case after correction in светах shades becomes less. In the image Interior.jpg it is not so noticeable. However, looked narrowly more attentively, you see that at magnification of gamma less detailed and unduly bright there is a window area (fig. 8.6).

Correction of gamma and stretching of a pitch range is very simple and effective method of correction of images with simple defects. Program Photoshop offers additional tools for the simplified correction of this type.

1. Pass to the document Bmw.jpg. In the protocol return to an initial state (before correction of levels).

2. Select command Brightness/Contrast (Brightness/visibility) I will change Adjust (Correction) of menu Image (Image). In the dialog box with the same name (fig. 8.7) only two scales — brightness and visibilities. Install suitable parameters. The most successful values of brightness +10, and visibilities +30 seemed to authors.

3. Push the button APPRX. Save a state picture. After that pass to a picture of a state of the document, made after correction in window Levels (Levels). Most likely, in quality you do not see a difference. Yes it also is not present. Therefore simple cases of correction are better for producing the most simple tool.

Command Auto Levels (Automatic correction of levels) operates is a command of direct action even easier. It is caused or button Auto (Car) of dialog box Levels (Levels), or from submenu Adjust (Correction) of menu Image (Image).

1. Again pass to not edited state of the image of the document Bmw.jpg.

2. Open dialog box Levels (Levels). To force the program to make automatic correction of levels, (Car) is enough to click on button Auto.

3. Compare also this result with remaining, received by manual adjustment of levels and command Brightness/Contrast (Brightness/contrast).

4. Automatic correction of color images, as a rule, is not ideal. But it is more successful for half-tone illustrations. Open the document Girl.jpg and fulfill correction by command Auto Levels (Automatic correction of levels). The image became contrast.

In the course of manual correction you cut edge levels if in them it is not enough пикселов. At automatic correction it is possible to set to the program percent cut пикселов in area светов and shades. It is very useful for removal of unduly bright levels in the images intended for the press, and for correction preventing on casual scratches and stains.

1. Push ALT key. Button Auto (Car) in window Levels (Levels) turns to button Options (Parameters). Click on it opens a window of adjustment of self-correcting Auto Range Options (Parameters of automatic adjustment of a range) (fig. 8.8).

2. By default in this window values of 0,5 % for black and white are defined. That is at automatic correction appropriate levels which contain less than 0,5 % пикселов, in светах are considered white, and in shades - as the black. Entering different values into fields, test their influence for result commands Auto (Car).

In the same submenu Adjust (Correction) is allocated also other command of direct action for correction of levels — Equalize (Alignment). As a result of its operation edge levels are strongly enough cut, and remained пикселы are arranged on a range with the greatest Possible uniformity.

1. Select this command for the source image Interior.jpg. The image became very bright. Пикселы, concentrated in dark tones, were aligned on all interval of brightness.

However effect of alignment very rough (fig. 8.9,). For easing of action of the last, just given command, dialog box Fade (Easing) is used.

2. Select command Fade to (Weaken) menu Edit (Editing), now it looks as Fade Equalize (to Weaken alignment). Dialog box Fade (Easing) (fig. 8.9,) opens. The program considers last modification in the image as a temporary layer, a transparency and which mode of superimposing can be changed. Move slider Opacity (Opacity) and look, as the effect from alignment of levels weakens. Install opacity of 58 % (fig. 8.9,).

3. In list Mode (Mode) superimposing modes are enumerated. Authors consider as the most comprehensible mode Normal (Normal). Set it and click on the button APPRX.

4. The given method of correction to us seemed to the most successful. Save a file in a working folder.