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Adobe Photoshop Elements 7Unleash the hidden performance of Elements
By Mark Galer
Focal PressCopyright © 2008 Mark Galer
All right reserved.
Chapter OneProject 1
Crop and Correct
This simple project will unmask some of the hidden features of the Straighten and Crop tools, enabling you to optimize your images for print or screen viewing. You will learn that you can straighten, resize and crop your image with just a few clicks, and that the Free Transform command can correct any unnatural perspective resulting from using wide-angle lenses. Quality starts here.
1. Open the image from the supporting DVD in the Standard Edit workspace. Click on the 'Straighten tool' in the Tools panel. Select the option 'Grow or Shrink Canvas to Fit' in the Options bar above the image window. Now click on the horizon line and, with the mouse button held down, drag a line along the horizon line of the image. The image will automatically be straightened.
2. Select the Crop tool in the Tools panel and view the options in the Options bar. When we size an image we should select the width and height in pixels for screen or web viewing, and in centimeters or inches for printing. Typing in 'px', 'in' or 'cm' after each measurement will tell Photoshop Elements to crop using these units. If no measurement is entered in the field then Photoshop Elements will choose the default unit measurement entered in the preferences (Preferences > Units & Rulers). The preference can be quickly changed by right-clicking on either ruler (select 'View > Rulers' if they are not currently selected).
3. The action of entering measurements and a resolution at the time of cropping ensures that the image is sized (pixel dimensions altered) and cropped (shaped) in one action. Entering the size at the time of cropping ensures the aspect ratio or shape of the final image will match the printing paper, photo frame or screen where the image will finally be output.
Note > If an aspect ratio or both width and height measurements are entered into the measurement fields, the proportions of the final crop will be locked. This new aspect ratio may differ from that of the original capture and this in turn may prevent you from selecting either the full width or full height of the image, e.g. if you have entered the same measurement in both the width and height fields the final crop proportions are constrained to a square.
4. Drag the cropping marquee over the image to create the best composition. Drag any of the corner handles, or click and drag inside the crop marquee, to adjust the composition and then commit the crop by clicking on the check mark or double-clicking inside the crop marquee. The image should get smaller on the screen as excess pixels are discarded. If the image grows on screen, Photoshop Elements is upsampling (adding pixels). This is caused by the dimensions in the Crop tool options being larger than the size of your original image, and can reduce the quality. It is important to save this cropped version using a different name to ensure the higher resolution master file is preserved.
Correct Camera Distortion
When a camera is tilted up or down with a short focal length lens (wide angle) the verticals within the image can lean excessively inwards or outwards (converging verticals). Professional architectural photographers use cameras with movements or special lenses to remove this excessive distortion. To correct perspective use the Correct Camera Distortion filter.
1. Select Filter > Correct Camera Distortion. The grid should be on by default and you can change its color if it's not clear against the subject you are viewing. The top slider in this dialog box corrects either barrel distortion or pincushion distortion, which sometimes results when using the extreme focal lengths of the zoom lens. Both result in curved straight lines which are usually most noticeable with the curvature of a horizon line when using a short focal length lens (wide angle).
2. To render all the vertical lines in the image used in this illustration parallel, drag the Vertical Perspective slider in the Perspective Control section of the dialog box to the left. Use the grid lines to align the verticals within the image. Use the keyboard shortcuts to access the Zoom tool (Control + Spacebar and Alt + Spacebar) if you need to zoom in on a vertical to check the accuracy of the correction. You may need to alter the angle to ensure absolute accuracy.
3. The Correct Camera Distortion filter also has control over vignetting (where the tone in the corners of the image appears darker or lighter than the overall tones within the rest of the image). Vignettes are often used for creative reasons to fade an image to black or white at the edges and corners. Some wide-angle lenses vignette when used at very wide apertures and these effects can be reduced or removed using the sliders in the Correct Camera Distortion dialog box. In the example image above a value of +35 is used to remove the darkened corners of the image that resulted from using a wide-angle lens. The Midpoint slider should be used to control the width of the correction, i.e. raising the value of the Midpoint slider will restrict the lightening effect to just the extreme outer regions of the image window whilst lowering the value will broaden the lightening effect. In later projects the Correct Camera Distortion filter can be used to creatively darken the corners of images to increase the sense of drama and mood.
Chapter TwoProject 2
This project will guide the user safety through the tricky mountain passes of this primary and essential technique used to achieve quality digital images. The adjustment feature is called 'Levels', but when you are presented with the virtual mountain range on opening the Levels dialog box, you begin to wonder what the clever people at Adobe were thinking of when they gave this indispensable adjustment feature its wonderful name (I think it's called irony).
Setting the black and white points
In the illustration above one might be forgiven for thinking that the black peaks in the dialog box are an indication of how high the mountains are in the image, but no, the pixel mountains (called a histogram) are really an indication of how many pixels of each tone are present in the image. If the image is dark then the pixel mountains or histogram in the dialog box will be higher on the left side. If the image is very light, the histogram will be taller on the right side. The first step in nearly all image-editing tasks is the need to optimize the tonality or dynamic range of the image by adjusting the Levels.
Finding your levels > To open the Levels dialog, go to the Enhance menu and choose Adjust Lighting > Levels.
If you are a newcomer to this dialog box you may simply want to click on the Auto button and then click OK. This simple procedure ensures the tonality of the digital image starts with a deep black and finishes with a bright white for optimum contrast and visual impact. If you want to perform the task manually click on the black input slider underneath the mountain range (the triangle on the left) and drag it to where the histogram begins to slope upwards on the left side. If you are now looking for the little triangle at the foot of the photographic mountains instead of the virtual ones, then I suggest you go and lie down for a moment and come back refreshed. Do the same with the white input slider on the right and you are almost finished. Click and drag the gray slider in the middle to make the image brighter or darker (depending on which way you drag the slider). If you want to start impressing the neighbors then you may like to start calling the gray triangle the 'Gamma slider'.
If you drag the sliders too far you will lose or clip information from the image file. Shadows will become black and highlights will become white (this is called clipping the shadows or highlights). Your detail will have sunk without a trace into the black holes of our virtual valleys (called level 0) or have been pushed off the top of the virtual peaks (called level 255). If you fear the numbers 0 and 255 (which every self-respecting photographer should) you could try the following tip. Hold down the Alt key and drag the Black or White input sliders towards the mountains (your image will disappear momentarily but fear not). As you move the slider closer to the middle, colors will start to appear in your main image window when information is being lost. Move the sliders back until these colors disappear, but no farther. If colors are still appearing in the image window with the sliders all the way back to the edge of the histogram then your image was either underexposed or overexposed by the camera. If you are really unlucky you will have lost detail both in the shadows and in the highlights as a result of the photographer's worst enemy - excessive contrast. Not even the magic called Photoshop Elements can dig you out of this hole, my friend.
A video tutorial is available on the DVD that takes you through a series of steps used to edit this image. This includes removing a color cast, setting the black and white points and changing the contrast and color of the foreground fields.
Localized adjustment of levels
1. In the image above the levels have been set so that the image file had both a black point and white point. The foreground still lacks localized contrast however. This is a result of the brightest tone in the foreground being Level 160. It is possible to expand the contrast of the foreground without clipping the lighter tones in the sky using the layer mask on the adjustment layer.
2. As you drag the white input slider to the left the sky will clip to white before any of the highlights appear in the foreground. The steel bars and brightest highlights just behind the base of the tree will start to appear first. Move the white input slider back a little until there is minimal clipping. Let go of the Alt key to see the effect this adjustment has had on the foreground contrast. Move the gray (Gamma) slider to the right to darken the image slightly. We have now increased the contrast in the foreground at the expense of the sky (which is now clipped). Sometimes things have to get worse before they can get better so select OK.
3. Increased contrast brings with it, increased saturation, which in this instance is an unwelcome visitor to the proceedings. We can remove the increase in saturation by simply setting the adjustment layer to Luminosity mode (so long as you don't have one of the painting tools selected the keyboard shortcut is (Alt + Shift + S). Select the gradient Tool in the Tools panel and in the Options bar choose the Black, White and Linear options. Drag a gradient from a short distance above the horizon line to a short distance below the horizon line. This will effectively shield the sky from the effects of this aggressive adjustment layer and return the tonality of the sky back to 'normal'. Normal does not mean dramatic and seeing as this is an exercise in dram we will se to rectify this in the next step.
4. In the Layers panel click on the Create a new layer icon. Hold down the Alt key and click on a dark area of the sky to sample the color. Select the Foreground to Transparent and linear options in the Options bar and drag a long gradient from the top of the image to the horizon line to darken the sky further which will give further emphasis to the foreground detail.
Chapter ThreeProject 3
All digital cameras capture in Raw but only digital SLRs and the medium-to-high-end 'prosumer' cameras offer the user the option of saving the images in this Raw format. Selecting the Raw format in the camera instead of JPEG or TIFF stops the camera from processing the color data collected from the sensor. Digital cameras typically process the data collected by the sensor by applying the white balance, sharpening and contrast settings set by the user in the camera's menus. The camera then compresses the bit depth of the color data from 12 to 8 bits per channel before saving the file as a JPEG or TIFF file. Selecting the Raw format prevents this image processing taking place. The Raw data is what the sensor 'saw' before the camera processed the image, and many photographers have started to refer to this file as the 'digital negative.' This digital negative allows you to take control over the conversion process to access maximum quality.
Excerpted from Adobe Photoshop Elements 7 by Mark Galer Copyright © 2008 by Mark Galer. Excerpted by permission of Focal Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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