Mon, 22 Aug 1994

Things you can do to bitmap images

By Zatni Arbi

JAKARTA (JP): Today, bitmap image editing tools have become so advanced and so sophisticated and every day we see so many of their new and creative uses around. Programs such as Adobe PhotoShop, Aldus PhotoStyler and CorelPHOTO-PAINT! provide us with a raft of powerful tools and exotic filters that help us create different effects automatically. Those with advanced mastery of these programs combine the uses of the tools to achieve stunning effects.

So, knowing that I only have rudimentary knowledge of image editing, I've always wanted to learn more about image editing and retouching using some of these leading software programs. The chance came as I got a copy of the newly released CorelPHOTO- PAINT! 5.0, and I embarked on some serious exploration into today's world of bitmap editing.

Unfortunately, bitmap editing is definitely not for those who still use a 386 machine, though. As my experience demonstrated, this paltry amount of power so frequently stretched my patience almost to its limit by forcing me to wait a long time for screen redraws before I could see the results of the action I'd taken. In addition, the system frequently crashed when I tried a series of more complicated actions.

Nonetheless, here are some effects that I've learned to use and would like to share with you--if you happen to be curious about image editing as well. Please remember that although I used CorelPHOTO-PAINT! 5.0 for the works that you see in the accompa nying illustration, you can easily find similar tools in the other top-notch image editing programs as well. In some cases, the other programs even beat CorelPHOTO-PAINT! in the quality of the resulting effects. The application of motion blur, shown in the BLUR.TIF window, would have given me a better result had I used the much less expensive Image-Pals 2.0.


Here's a method to get an image with the right dimension that I wish I had learnt long ago. Formerly, I would just resize a bitmap image to fit my need. I would import a bitmap image into PageMaker or CorelDRAW! and resize it using the pick tool. The results were unpredictable; sometimes I got a smooth printout, sometimes it was full with rough and ugly rasterized surface.

If you rescale a bitmap image, it is important to use the correct enlargement factor. In PageMaker and CorelDRAW!, to ensure that you get the optimum rescaled size for your bitmap image, you have to hold down the Shift key as you drag the rescaling handle--usually the ones on the corners. The problem is, the right size after rescaling may not be the right one for your layout. Whenever that is the case, you'll have to make a compromise between the quality of the bitmap image and the size of the picture.

The resampling command, found in most up-to-date bitmap editing programs, offers a better solution. Take a look at the picture in the WOMAN.TIF window in the illustration. I have resampled the image into a larger one, using the same resolution and color depth (color depth means the number of colors in the picture, whether 16, 256, or 16,7 million colors).

The reason resampling is a better method to enlarge or reduce the size of an image than just resizing is that you can apply the anti-aliasing technique for inserting new pixels. This technique chooses a pixel color that is the average between two adjacent original pixels. A different technique in CorelPHOTO-PAINT! is stretching and truncating, but the result is not as smooth as anti-aliasing.

When I resampled the image, I also specified that the new image should be 50 percent bigger. With a little calculation, you can resample an image so that the resulting one will fit exactly into the frame that you've prepared for it in your page layout. The best thing about resampling instead of resizing an image is that--as you can see in the illustration--the quality of the image does not change, unless you resize it again. In fact, you can even improve the quality by modifying the parameters, such as the number of colors if you're using a color printer or a 24-bit color video subsystem.

Motion blur

At the bottom center of the illustration you'll find two images, each containing a picture of two motorcyclists on a race track. I've applied the Motion Blur effect to the one in the BLUR.TIF, which has given the picture the illusion of movement.

There are two parameters in the Motion blur effect that you can play around with. One is the direction--whether up, down, left, right or diagonal. The other is the speed of the motion.

Had I selected the pictures of the two racers with the lasso tool, the result of the motion blur effect would have been more realistic, as the background would have remained sharp. As it is, the image looks as if it was a photograph taken with a moving camera.


Applying the Emboss effect gives the impression that the image has been chiseled into a flat surface. Usually this particular effect uses gray, light gray or dark gray to simulate a stone wall.

In most programs, you can specify the direction of the light--whether from the top, the bottom, left, right or diagonally. In some programs--unfortunately not in CorelPHOTO- PAINT! 5.0--we can also specify the depth of the emboss.

There are two important things to take into account when using the Emboss effect. First, you have to choose the right font for the text. Fonts with too many slanting lines do not make a good emboss effect. On the other hand, rather boxy-looking fonts give a nice effect. In the illustration, I've used USABlack for the text.

Second, different directions of lighting will give different results. Therefore, you should experiment with different lighting directions to find the one that gives the best readability. In the illustration, I added another effect to the emboss. First I created a rectangle mask around the text, and then I applied the one-color granite canvass mask. The result would look much more impressive in full color.


Take a look at the image in the VIGNETTE.CPT window. It looks as if the text THE JAKARTA POST had been painted on a wall with a rough surface, and a spotlight were used to light it. In full color, the effect is much more eye-catching than in grayscale.

I created the bitmap by first choosing yellow as the solid fill color and applying STUCCOC.PCX as the canvas. Then I chose bright red as the color, using the Color Roll-up. I added the text, using the Algerian font with 72 point size. Finally, I changed the color in the Color Roll-up to brown and applied the Vignette effect using the pen color option.

Next week we'll explore some more of the special effects that you can achieve. Again, if you're lucky enough to have a 486DX2- 66 machine with 16 MB of RAM, you are free to explore more complicated combinations of tools.

In the meantime, here's some more information on CorelDRAW! 5.0's secret screens. If you don't press and hold down the Shift key when you double-click on the icons in the About CorelDRAW! dialog box, you'll get a daylight version of the show. Now, click the right mouse button once, and you'll see something on the screen. Click twice, you'll see two of them. You can see only two of them at any given time, though. Wait until one of them disappears before you click the right mouse button again.

And now try this: Hold down the Shift key when you double- click on the icon in the dialog box. You'll get the night version of the show. Click with the right button, and you'll see spectac ular fireworks in the sky!