The Hidden Power of Photoshop Elements 4 PHẦN 2 pps

Either of these choices poses a trade-off. In creating more than one image, you sacri- fice valuable time in repeating processes for correction on different versions of an image. It is often self-defeating to work on two images to produce the same results (even using a detailed script) because the difference in size and volume of information in the image will produce different results with the same application of tools. In creating one image and resizing, you have to allow either interpolation of new image information or decima- tion, neither of which may be the optimal process. You can’t work on small images and resize up because detail will not be present. The best way to go about working with multipurpose images is usually to work with them at the highest resolution and then resize them smaller. Working at the higher of two or more resolutions retains the details for the higher-resolution presentations and deci- mates detail that will not be reproducible at lower resolutions. Softening or other ill effects from severe resizing can be countered somewhat by sharpening. A similar concept in retaining detail holds true when considering color depth. You will want to work in larger color spaces and at greater color depth to retain image detail and then reduce color detail and move to smaller color spaces after making corrections to reduce loss. You will most often use images from your digital camera at full resolution in RGB during corrections before reducing color and resolution for specific purposes. Can You Have Too Much Resolution? There are two answers to the question of whether or not you can have too much resolu- tion: yes and no. The answer depends on whether there are other circumstances that make high-resolution images a waste because the information won’t ever be used. There does come a point where the amount of image information is simply too much for the pur- poses of the image as it is being applied, or it gets so fine that more information doesn’t really reveal more useful detail. For the most part, you want all the detail that you can get in your source images from a digital camera. Consumer digital cameras are not so powerful that you will have enormous file sizes that are unwieldy—though you may need to consider alternatives for archiving images and image storage (on camera and off) to make the most of your equipment. Stor- ing your images at high resolution will allow you to return to them for other purposes in the future. See “(Un)Sharpening and Boosting Contrast” in Chapter 5 for more information on sharpening. can you have too much resolution? ■ 11 4456c01.qxd 3/1/06 3:04 PM Page 11 Exceptions to the high-resolution rule happen only when high resolution is absolutely overkill for the purposes that you took the image in the first place. For example, if there are some items that you want to put on eBay that don’t require a lot of magnification to see product quality or details, then you may need just enough resolution to show that the item is intact. Taking a full-resolution image may not be necessary, and large image down- loads may annoy, rather than attract, potential buyers. If you are taking just a few images of this sort, it may be just as easy to take the high-resolution image and resize the image smaller later (especially if you find you have to look for the camera’s manual to figure out how to change the resolution settings). Quality in this case is hardly the issue. Images that you obtain using a scanner or scanning service fall into a similar category. You will want to get as much detail as you can from a scan, but at some point you will be examining the grain of the film or paper in the print rather than extracting detail from the existing image. If you are scanning an image from a newspaper, you can use less resolution (samples) than if you scan from a negative, because the resolution of newspaper printing will be far lower (see Figure 1.2). The detail of your source can dictate the resolution as well as the application. If you are a casual shooter and only send photos to relatives via e-mail, keep in mind that an image will display at about three times the size in a web browser (72 ppi) than it does in print (240 ppi). So even resolution that seems low can be more than you really need depending on what you do. When going to print, too much image information can slow down processing and can be overkill. If you have a 5 ″ × 7″ image at 240 ppi, that will be enough to print at that size for many purposes. That is just 1200 × 1680 pixels, roughly what you get from a 2 mega- pixel camera. If you envision doing larger prints of the same quality, you will usually need more resolution (depending on the output devices). On the other hand, using that same image without resampling for a 2 ″×2.8″ image in a magazine is overboard: you’ll have roughly twice the resolution you really need. That additional resolution taxes com- puter imaging resources and will not improve your result. Imaging equipment ends up just crunching the image information and decimating detail, likely using a simple averag- ing technique with no sharpening. What that means is you may even get a better result if you resize the image correctly to a lower resolution on your own and sharpen the result. See the chapters in Part Vand the Appendix for more information about printing and resolution. If you think you might ever use the shot for more than one purpose, grab all the resolution that you can with your digital camera. 12 ■ chapter 1: Resolution: The Cornerstone of Image Detail 4456c01.qxd 3/1/06 3:04 PM Page 12 Figure 1.2 If you’re scanning or photographing this image from newsprint, the detail soon runs out, making higher- resolution scans or photos superfluous. can you have too much resolution? ■ 13 4456c01.qxd 3/1/06 3:04 PM Page 13 You may want to plan a little for the future; not only may technology improve to demand more resolution from images to make the best prints, but your needs may change and additional resolution may leave you with a little leeway to take advantage of future changes. Use resolution to your advantage, rather than just assuming it is correct. So, can you have too much resolution? Yes, but usually only in applying the images (in print and on the Web). Traditionally, the push has been toward more resolution and greater defini- tion. However, with newer consumer digital cameras capturing larger images, understand- ing how to apply and use image resolution becomes more important. Get what you can for archiving and storing images, but target that resolution to output and display sizes as needed. 14 ■ chapter 1: Resolution: The Cornerstone of Image Detail 4456c01.qxd 3/1/06 3:04 PM Page 14 Chapter 2 Seeing Images as Color, Contrast, and Tone Without light, there would be no images. Light is what shapes the subject of images. It strikes an object that you are photographing, reflects through the camera lens, and is cap- tured in the exposure as color, contrast, and tone. Light shapes the object, because shadows and highlights define object contour. Resolution allows you to capture image detail, but it is the subtle interplay of tones, contrast, and color that gives shape to objects in the image. Understanding how color, contrast, and tone are captured and how they work together will help you better understand your images and how the corrections you make effect change. Tone and color are more intermeshed than most people think: brightness affects color and intensity throughout the spectrum. Color can be captured with different depth (really, more color resolution) and stored in different file types as color and tone components. Rendering image color faithfully in print and on screen makes what you see on screen essential to your results. This chapter looks at the relationship between color and tone, bit depth, and displaying images correctly as components of the image editing process. Tonal Range, Brightness, Contrast, and Image Dynamics Color as Tone Types of Color Gaining Perspective on Color Management Making What You See What You Get: Monitor Calibration and Color Preferences 4456c02.qxd 3/1/06 3:04 PM Page 15 Tonal Range, Brightness, Contrast, and Image Dynamics Tonal range is the difference between the lightest and darkest image areas. The greater the difference is between the lightest and darkest areas of an image, the greater the tonal range. Brightness serves as a measure and limiting factor for both tonal range and contrast. It is a measure of the median luminosity of an image from dark to light. The way light and dark tones play against one another is contrast. The more stark the difference is between light and dark image areas, the greater the contrast. If tonal range, brightness, and contrast are not balanced correctly, an image will appear too light, too dark, too flat, or too harsh and contrasty, as illustrated in Figure 2.1. Creating a dynamic image starts with making the most of the tonal range that exists in the image. Contrast (or lack of contrast) between tones within that range helps define image character. Not every image will naturally have high contrast and a broad tonal range. Some images may be naturally high key (light, usually with moderate to low Too light Too dark Too much contrast Balanced brightness and contrast Not enough contrast Figure 2.1 One image can look many different ways, but the best way usually uses full tonal range and flat- tering contrast. 16 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 4456c02.qxd 3/1/06 3:04 PM Page 16 contrast), low key (dark, usually with moderate to low contrast), or simply low contrast. Usually, the goal of correction is to maintain the natural character, or key, of an image while adjusting tone and contrast to enhance and improve dynamics. If there are 255 possible grays for your image, and you use only 100 of those, the image is really only about 40 percent as dynamic as it might be. If you adjust the tonal range, the image can become more visually dynamic; if you adjust with care, you won’t lose the natural quality of the image. Both tone and contrast work in almost the same way in color and black-and-white images: you want to make the most of and expand tonal range and dynamics while main- taining image character. The difference is, when you extend the tonal range in a black-and- white image, you get more potential grays (tones); when you make similar adjustments in color images, you get more potential colors as well as a full range of tone. Color as Tone Color is a pretty simple thing to manage if you’re picking out clothes, drapes, or uphol- stery. In those cases it is already mixed and applied for you. If you don’t have experience with color mixing, it isn’t until the first time you actually try to correct the color of an image that the complexity of color comes alive. If you’ve never had any training in art and color theory, understanding how color works can be a little confusing. Add to that the existence of different color modes (theoretical ways of defining color), and color becomes still more complex. Even more confusion can grow from the fact that color is often stored in your digital images as grayscale components. Because color can be split into simple grayscale components, it is important to understand how grayscale (tone, brightness, and contrast) can also define color. However complex, you have to understand color and how it works in digital images to apply it and achieve the results you want. For the most part, images that you will work with in color will be in RGB mode. RGB stands for red, green, and blue. It is based on an additive light-based color theory: differ- ent combinations and intensities of red, green, and blue lights make up the set of available colors. As the red, green, or blue lights are made brighter and applied with more intensity, the resulting color gets brighter, and colors mix in these varying intensities to form other colors. Full intensity of red, green, and blue results in white; lack of red, green, and blue results in black. It is a theory that works great with projection, such as on your monitor and some projection TVs. Breaking images into their component RGB colors is how your monitor displays color, and often RGB color is how image detail is captured by a scanner or digital camera. Each color you see is made up of these three color components in different combina- tions. In 8-bit digital images, each of the three components has 256 intensities (Elements does have 16-bit capability, which is discussed more later in this chapter and in the “Bit color as tone ■ 17 4456c02.qxd 3/1/06 3:04 PM Page 17 Depth” section of the Appendix). The grayscale representations of the intensity of the red, green, and blue are stored as grayscale information in your image files. Light coming into a camera or sensed by a scanner is actually broken into these three components to be stored as intensity of the component color. Later the information is reassembled, allowing your computer to reproduce full-color images from the RGB components. This theory and practice have been around for quite a while. One of the earliest photo- graphers to create color images did it in Russia in the early 1900s, before there was actual color film. Sergei Mikhailovich Prokudin-Gorskii (1863–1944) made glass plates three at a time when he took pictures with a specially designed camera, filtering for the red, green, and blue components of light to record the strength (tone) of each component on what was essentially grayscale film. The plates would record the captured light as grayscale, and then using a special projector, Prokudin-Gorskii would project the images simultaneously with red, green, and blue filters to reproduce the color images on a projection screen. Figure 2.2 shows one of Prokudin-Gorskii’s images; a composited version of this image is also available as Kush-beggi.psd in the Chapter 2 folder on this book’s CD. (These plates are from the collection at the U.S. Library of Congress, which can be accessed at http://lcweb2.loc.gov/pp/prokquery.html.) A very similar type of light separation is accomplished when shooting color film. Inside each of your color images are the primary source colors: red, green, and blue. These source colors are stored as grayscale representations and mappings of the intensity of red, green, and blue light in every pixel in your image. When you work on color images, the changes that you make during correction and changes affect all three of the source col- ors at the same time. Using the right techniques (which we will look at in this book), you can separate out the grayscale representations of all the color components of your images and retrieve them for use in adjusting your image dynamics, tone, contrast, and color. Breaking down color information into color components may not always be to your advantage when making corrections, but it can often be helpful when trying to isolate damage and perform advanced color correction. The ability to make separations into image components is a key concept of this book. If you understand how to make compo- nent separations and how these separations combine to create your images, it opens a world of possibility for improving images. Photoshop has a palette called Channels, which is not included with Photoshop Elements. The Channels palette, like the Layers palette, enables you to edit color components and manipulate them separately (in RGB as well as other color modes). This can be a great tool in making complex color corrections. Even though there is no formal Channels palette in Elements, this book shows you how to access and alter channel information easily, just as if you had a Channels palette working for you. For the sake of this book and working with Elements (rather than Photoshop), channels are referred to as components. 18 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 4456c02.qxd 3/1/06 3:04 PM Page 18 As Prokudin-Gorskii did in creating his “color” images, we can re-create representation of color as grayscale components by filtering digital images using functionality in Elements. When the color components are separate, they can be adjusted one at a time, simplifying Original plates Blue plate close-up Green plate close-up Red plate close-up Figure 2.2 This image by Prokudin-Gorskii (a portrait of Minister of the Interior Kush- Beggi) was taken around 1910 by separating color into grayscale RGB plates. Scans of the glass plates can be composited to achieve a full-color result (as we will do in an exercise in Chapter 4). color as tone ■ 19 4456c02.qxd 3/1/06 3:04 PM Page 19 the way you work with color. This can help when correcting color-specific defects, in sim- plifying an approach to images and corrections, in developing a better understanding of what happens when you apply a tool to color images, and in doing the most complex color alterations and corrections. Let’s look at color types and color management, which affect the way color is stored and represented. Types of Color Color in your images can be measured in several ways. Photoshop Elements uses color modes, which as I said earlier are really just different ways of depicting color and tone. The following are the four modes you can use: • RGB • Indexed Color • Grayscale • Bitmap Image color mode and file type are two very different things. Knowing which color modes appear in which file types (and which file types to use with a certain color mode) is often essential for correctly purposing your images. For the most part, people using Photoshop Elements will be working with 8-bit color images in RGB mode. This mode offers the broadest flexibility for tool use and is the mode most images are in when captured or created. As I have said, RGB refers to the type of color storage; in this case information is stored as red, green, and blue components. 8-bit refers to the exactitude of the color representation, or the number of variations that can be stored per pixel in a color component. In 8-bit RGB, 256 possible tonal variations in each of the three color components lead to over 16 million different possible color vari- ations (256 × 256 × 256 = 16,777,216). That’s one big box of Crayolas! In fact, it is the largest color set of any of the color modes you will be working with in Elements, except when using 16-bit RGB. A larger number of possible colors in your image allows finer distinction between colors and helps changes that you make to images blend more evenly without noticeable shifts, or banding, between colors. 16-bit is perceived to be an advantage over 8-bit, with 35,184,372,088,832 potential colors. Images can theoretically have better integrity, and changes are less apt to damage Later in this section and elsewhere in the book we’ll look at other color modes, including LAB, CMYK, RGBL, and Duotone. These are not technically working color modes in Elements, but you can achieve separations for these color models and save the separations to files using Elements. 20 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 4456c02.qxd 3/1/06 3:04 PM Page 20 [...]... uses the colors in the image and maps them according to the profile assigned the actual content of the image (numbers in the file) does not change, but the look of it very well might (especially if the profile assigned is not the working color space) The intensity of the color change for the image depends on the differences between the original color space and the assigned profile Converting to a profile... color change The content of the image will be converted from one profile to another, and the content of the image (numbers in the file) will change in accordance with the conversion The difference between assigning a profile and converting to one is that the goal of converting to a profile is to retain color as is Assigning a profile just assumes there is no previous profile and uses the color by numbers... mode allows a maximum of 25 6 colors and can include transparent values The colors are created as a table by using hex values: sixcharacter codes that represent specific colors (see the hextable.html Chart in the Chapter 2 folder on the Hidden Power CD) The colors cannot be mixed and must be one or another of the colors in the table The goal of limiting colors, especially in the case of Web images, is to... Color Profile ➔ Remove Profile This strips off the existing profile You may see an immediate change in the image 4 Choose either Image ➔ Convert Color Profile ➔ Apply sRGB Profile (to convert to sRGB) or Image ➔ Convert Color Profile ➔ Apply Adobe RGB Profile (to convert to Adobe RGB If you try assigning and converting profiles with the berries.psd file from the Hidden Power CD, you can compare the results... based on the steps described in the preceding section Most of these are standard tools you already have in Photoshop Elements; others are addins you will find on this book’s companion CD These Hidden Power tools” can simplify processes or add new functionality to Photoshop Elements See the Hidden Power Tools” section of the book’s introduction for instructions on how to load and access these additional... obtain the information, write it down I usually write the settings right on the cover of the monitor manual for easy reference Color temperature reflects the monitor display color for the white point, which really is a measure of the color of white on your monitor It is usually 6500, 7500, or 9300 degrees on the Kelvin scale The higher the number, the more blue (or cool) the white is; the lower the number,... in the Save As dialog box Opening a new ■ 39 40 ■ chapter 2: Seeing Images as Color, Contrast, and Tone image or an image with no existing profile will cause Photoshop Elements to retain the profile with the image based on the color mode RGB will have the Adobe RGB (1998) profile Indexed Color will have the Adobe RGB (1998) profile Grayscale will have a Dot Gain 20 % profile Bitmap will have no profile... subtractive (the more ink/color you add, the darker it gets, because the light striking the color is absorbed) CMYK ink is most often applied in an array of printer dots; as the dots overlay, the result becomes darker and the ink colors mix Figure 2. 5 shows how two ink halftones combine for a darker result Figure 2 .4 The magnification of a portion of the original bitmap image reveals the bitmap patterning... embed the profile (tag the files as Adobe RGB) and ensure, along the route of the image, that the profiles are respected In other words, using Adobe RGB is a commitment to using embedded profiling for your images and, most likely, color management that respects profiling Using sRGB will not require embedding profiles for the most part to achieve good results In other words, the working color space and the. .. folder, find it on the Photoshop Elements CD 4 Click Step By Step This will lead you through the process of calibrating and creating an ICC profile for your monitor Click the Next button The initial Adobe Gamma screen 32 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 5 In the Description field, type a name for the profile you will be creating (Figure 2. 7) You can enter a lot of information here, . the Chap- ter 2 folder on the Hidden Power CD). The colors cannot be mixed and must be one or another of the colors in the table. The goal of limiting colors, especially in the case of Web images,. copies of the original images before converting them to 8-bit. 24 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 44 56c 02. qxd 3/1/06 3: 04 PM Page 24 When possible, working in 16-bit rather. Color Space” in the next section. 28 ■ chapter 2: Seeing Images as Color, Contrast, and Tone 44 56c 02. qxd 3/1/06 3: 04 PM Page 28 To be reasonably successful with color management, the Photoshop Elements