Photoshop 6 for Windows Bible- P32 pot

11 Chapter A ✦ Constructing Homemade Effects Figure A-13: To blur more subtly, increase the central matrix value and the Scale value by equal amounts. Edge-detection Many of you are probably beginning to get the idea by now, but just in case you’re the kind of person who believes that friends don’t let friends do math, I’ll breeze through it one more time in the venue of edge-detection. If you really want to see those edges, enter 1s and 2s into the neighboring options in the matrix and then enter a CMV just small enough — it’s a negative value, after all — to make the sum 1. Examples appear in Figure A-14 for your viewing pleasure. Figure A-14: To create severe edge-detection effects, enter a negative CMV just small enough to compensate for the positive values in the matrix. 12 Extra Reading ✦ Photoshop 6 for Windows Bible To lighten the edges and bring out the blur, raise the CMV and enter the resulting sum into the Scale option box. The first example in Figure A-15 pushes the bound- aries between edge-detection and a straight blur. Figure A-15: To blur the edges, increase the central matrix value and then enter the sum into the Scale value. Non-1 variations Every image shown in Figures A-7 through A-15 is the result of manipulating matrix values and using the Scale option to produce a sum total of 1. Earlier in this chap- ter, I showed you what can happen if you go below 1 (black images) or above 1 (white images). But I haven’t shown you how you can use non-1 totals to produce interesting, if somewhat washed-out, effects. The key is to raise the Offset value, thereby adding a specified brightness value to each pixel in the image. By doing this, you can offset the lightening or darkening caused by the matrix values to create an image that has half a chance of printing. Lightening overly dark effects The first image in Figure A-16 uses nearly the exact same values used to create the extreme sharpening effect in the last image of Figure A-8. The only difference is that the CMV is 1 lower (8, down from 9), which in turn lowers the sum total from 1 to 0. The result is an extremely dark image with hints of brightness at points of high con- trast. The image looks okay on screen—actually, it looks pretty cool because of all those little star-like sprinkles in it — but it’s likely to fill in during the printing pro- cess. If the first image in Figure A-16 looks like anything but a vague blob of black- ness, it’s a miracle. Most people would kiss this image good-bye, and rightly so. It’s too darn dark. 13 Chapter A ✦ Constructing Homemade Effects Figure A-16: Three examples of sharpening effects with sum totals of 0. I lightened the images incrementally by entering positive values into the Offset option box. To prevent the image from filling in, lighten the image using the Offset value. Photo- shop adds the value to the brightness level of each selected pixel. A brightness value of 255 equals solid white, so you don’t need to go too high. As illustrated by the last example in Figure A-16, an Offset value of 100 is enough to raise most pixels in the image to a medium gray. Figure A-17 shows the results of lightening an overly dark edge-detection effect using the Offset value. Figure A-17: Three examples of edge-detection effects with sum totals of 0, lightened incrementally by using progressively higher Offset values. 14 Extra Reading ✦ Photoshop 6 for Windows Bible Darkening overly light effects You also can use the Offset value to darken filtering effects with sum totals greater than 1. The images in Figures A-18 and A-19 show sharpening and edge-detection effects whose matrix totals amount to 2. On their own, these filters produce effects that are too light. However, as demonstrated in the middle and right examples in the figures, you can darken the effects of the Custom filter to create high-contrast images by entering a negative value into the Offset option box. Figure A-18: Three examples of sharpening effects with sum totals of 2. I darkened the images incrementally by entering negative values into the Offset option box. Figure A-19: Three examples of edge-detection effects with sum totals of 2, darkened incrementally with progressively lower Offset values. 15 Chapter A ✦ Constructing Homemade Effects Using extreme offsets If a brightness value of 255 produces solid white and a brightness value of 0 is solid black, why in blue blazes does the Offset value permit any number between negative and positive 9,999, a number 40 times greater than solid white? The answer lies in the fact that the matrix options can force the Custom filter to calculate brightness values much darker than black and much lighter than white. Therefore, you can use a very high or very low Offset value to boost the brightness of an image in which all pixels are well below black or diminish the brightness when all pixels are way beyond white. Figure A-20 shows exaggerated versions of the sharpening, blurring, and edge- detection effects. The sum totals of the matrixes are –42, 54, and 42, respectively. Without some help from the Offset value, each of these filters would turn every pixel in the image black (in the case of the sharpening effect) or white (blurring and edge-detection). But as demonstrated in the figure, using enormous Offset numbers brings out those few brightness values that remain. The images are so polarized that there’s hardly any difference between the three effects, except that the first image is an inverted version of the other two. The difference is even less noticeable if you lower the opacity of the effect using Filter ➪ Fade, as demonstrated in the sec- ond row of examples in Figure A-20. Figure A-20: You can create high-contrast effects by exaggerating all values in the matrix and then compensating by entering a very high or very low Offset value (top row). When you back off the effect using Filter ➪ Fade (bottom row), these dramatic effects are barely discernible. 16 Extra Reading ✦ Photoshop 6 for Windows Bible Figure A-21: Enter positive matrix values in a horizontal formation (left) or vertical formation (middle) to create slight motion blurs. By positioning positive values in opposite corners of the matrix, you create a vibrating effect (right). Directional sharpening To selectively sharpen edges in an image based on the angles of the edges, you can organize negative and positive matrix values into rows or columns. For example, to sharpen only the horizontal edges in an image, fill the middle row of matrix options with positive values and the rows immediately above and below with negative val- ues, as demonstrated in the left example in Figure A-22. Similarly, you can sharpen only the vertical edges by entering positive values in the middle column and flank- ing the column on left and right with negative values, as shown in the middle exam- ple in the figure. In the last example, I arranged the positive values along a diagonal axis to sharpen only the diagonal edges. You even can combine directional sharpening with directional blurring. Figure A-23 shows the first example from Figure A-22 blurred both horizontally and vertically. To blur the image horizontally, as in the middle example of Figure A-23, I added pos- itive values to the extreme ends of the middle row, thereby extending the range of the filter and creating a sort of horizontal jumbling effect. To blur the image verti- cally, as in the final example of the figure, I added positive values to the ends of the middle column. 17 Chapter A ✦ Constructing Homemade Effects Figure A-22: Arrange positive values in a row (left), column (middle), or along a diagonal axis (right) to sharpen horizontal, vertical, and diagonal edges exclusively. Figure A-23: The image from Figure A-22 (left) blurred horizontally (middle) and vertically (right). 18 Extra Reading ✦ Photoshop 6 for Windows Bible Embossing So far, we aren’t going very nuts, are we? Despite their unusual formations, the matrix values in Figures A-21 through A-23 still manage to maintain symmetry. Well, now it’s time to lose the symmetry, which typically results in an embossing effect. Figure A-24 shows three variations on embossing, all of which involve positive and negative matrix values positioned on opposite sides of the CMV. (The CMV happens to be positive merely to maintain a sum total of 1.) Figure A-24: You can create embossing effects by distributing positive and negative values on opposite sides of the central matrix value. This type of embossing has no hard and fast light source, but you might imagine that the light comes from the general direction of the positive values. Therefore, when I swapped the positive and negative values throughout the matrix (all except the CMV), I approximated an underlighting effect, as demonstrated by the images in Figure A-25. In truth, it’s not so much a lighting difference as a difference in edge enhancement. White pixels collect on the side of an edge represented by positive values in the matrix; black pixels collect on the negative-value side. So when I swapped the loca- tions of positive and negative values between Figures A-24 and A-25, I changed the distribution of white and black pixels in the filtered images. 19 Chapter A ✦ Constructing Homemade Effects Figure A-25: Change the location of positive and negative matrix values to change the general direction of the light source. Embossing is the loosest of the Custom filter effects. As long as you position posi- tive and negative values on opposite sides of the CMV, you can distribute the values in almost any way you see fit. Figure A-26 demonstrates three entirely arbitrary arrangements of values in the Custom matrix. Figure A-27 shows those same effects downplayed by raising the CMV and entering the sum of the matrix values into the Scale option box. Figure A-26: You can create whole libraries of embossing effects by experimenting with different combinations of positive and negative values. 20 Extra Reading ✦ Photoshop 6 for Windows Bible Figure A-27: To emboss more subtly, increase the central matrix value and the Scale values by equal amounts. Incidentally, the main advantage of using the Custom filter rather than using Filter ➪ Stylize ➪ Emboss to produce embossing effects is that Custom preserves the colors in an image while Emboss sacrifices color and changes low-contrast portions of an image to gray. Figure A-28 shows the matrix values from the first example of Figure A-26 applied to a color image. It also shows examples of other Custom effects, including variations on sharpening and edge-detection. If you become enthralled with convolution kernels and you feel compelled to explore them in more detail, you may want to check out a $200 plug-in called KPT Convolver from MetaCreations. Although steeply priced, it permits you to explore convolutions using a more intuitive interface and without using any math. Convolver doesn’t do anything that you can’t already do with the Custom filter, but it can simultaneously apply different convolutions to separate color channels, and it permits you to investigate filtering possibilities that you aren’t likely to discover on your own. [...]... center of the image For example, if 39 40 Extra Reading ✦ Photoshop 6 for Windows Bible you enter rad(d– 16, m– 16, 0) into the red channel, you rotate the contents of the channel 16 increments (about 6 degrees) counterclockwise and distort its center outward The upcoming step-by-step example uses this function The function rnd generates a random number between two extremes, which is great for creating noise... that are forever changing The r that first appears in the R option box, for example, represents the brightness value that currently occupies the PBE in the red channel So by entering r in the R option box, you tell Photoshop to change the red PBE to its current color, which is no change whatsoever It’s just Adobe’s way of creating a clean slate for your work 37 38 Extra Reading ✦ Photoshop 6 for Windows. .. and restart Photoshop Choose Filter ➪ Synthetic ➪ Filter Factory to display the Filter Factory dialog box, shown in Figure A-44 By any account, I think this has to be the scariest dialog box ever put before a Photoshop user Yours is probably even more scary The R option box contains a little r, the G option box contains a little g, and the B option box 35 36 Extra Reading ✦ Photoshop 6 for Windows Bible... without them you get a single-shot filter like Photoshop s Sharpen More or Facet effects Tip The Load and Save buttons enable you to load formulas from disk or save them for later use or editing If you’ve had a long hard day and it’s time to go home — or you’re already home and you want to go to bed — don’t forget to save the formulas to disk Every time you restart Photoshop, the Filter Factory reverts to... disk in the native Photoshop 2.0 format Then choose Filter ➪ Distort ➪ Displace, specify the desired settings, and select the version of the image saved to disk Figure A-41 shows three applications of this effect, once applied at 10 percent exclusively horizontally, the next at 10 percent vertically, and the last at 10 percent in both directions 33 34 Extra Reading ✦ Photoshop 6 for Windows Bible Figure... light For example, in the revised dmap channels shown in the left column of Figure A-32, the gray values progress slowly from gray to black, abruptly from black to gray to white, and then slowly again from white to gray Slow light to dark, fast dark to light The results are smoother image distortions, as demonstrated in the middle and right columns of the figure 25 26 Extra Reading ✦ Photoshop 6 for Windows. .. for Windows Bible contains a little b Throw in a few arbitrarily named slider bars, and you have the perfect formula for striking terror in the unsuspecting image-editor’s heart Figure A-44: The Filter Factory dialog box containing the formulas for adding a series of grid lines to an image The formula in the R option box is partially cut off because it’s too long to fit on two lines Note If the command... displacement map tell Photoshop which pixels to affect and how far to move the colors of those pixels: ✦ Black: The black areas of the displacement map move the colors of corresponding pixels in the selection a maximum prescribed distance to the right and/or down Lighter values between black and medium gray move colors a shorter distance in the same direction 21 22 Extra Reading ✦ Photoshop 6 for Windows Bible... dmap must be a color or grayscale image, and you must save the dmap as a flattened image in the native Photoshop file format (If you want to be absolutely sure there are no layers, use the Photoshop 2.0 format.) The Displace command does not recognize PICT, TIFF, or any of the other nonnative file formats Who knows why? Those programmers move in mysterious ways Chapter A ✦ Constructing Homemade Effects... middle image at 10 percent and the right image at 20 percent Therefore, the colors in the right image travel twice the distance as those in the middle image, but all colors travel the same direction (The upcoming section “The Displace dialog box” explains exactly how the percentage values work.) 23 24 Extra Reading ✦ Photoshop 6 for Windows Bible Figure A-30: The results of applying a single-channel . dramatic effects are barely discernible. 16 Extra Reading ✦ Photoshop 6 for Windows Bible Figure A-21: Enter positive matrix values in a horizontal formation (left) or vertical formation (middle) to create. and vertically (right). 18 Extra Reading ✦ Photoshop 6 for Windows Bible Embossing So far, we aren’t going very nuts, are we? Despite their unusual formations, the matrix values in Figures A-21. box. Figure A- 26: You can create whole libraries of embossing effects by experimenting with different combinations of positive and negative values. 20 Extra Reading ✦ Photoshop 6 for Windows Bible Figure