Creating A Web Plaque: A GIMP Tutorial
http://www.disordered.org/GimpPlaque.html
Making the plaque surface
Our next task is to create the surface texture for the plaque. We'll use a
color from our graphic as the basis of our texture. Assuming that the artist
knows how to pick reasonable colors, that will give us a combination that
works well together.
-
Create a new canvas of the same size as our plaque. Use the Plasma Cloud plugin (Filters -> Render -> Plasma Cloud) to generate a pattern of color in the canvas. Here we used the default values for the plugin.
-
Gaussian blur (Alt-Shift-B) the clouds by 3 pixels to remove the rough transitions. Grayify the image (Filters -> Map -> Grayify). We need to remove all the color from the image before we add in the color we want.
-
Now we need to choose a color for the plaque. Switch to the Color Picker (O). Click on a part of our image (the baby gnu) that we want to match, like his blue scarf. Write down the red, green and blue values reported by the Color Picker: 149, 197, 251.
-
To match this color, we'll Decompose our gray plasma into its component parts (Filters -> Conversions -> Decompose). Choose the RGB decomposition. We'll get three identical gray images.
-
Start with the canvas labeled "red". Click near the upper left corner of the image to get its intensity: 134. Bring up the Brightness / Contrast / Gamma plugin (Filters -> Map -> B/C/G) on this canvas. Adjust the brightness higher until clicking on the canvas shows a Color Picker intensity near the one we wrote down: 149. When we get the value we want, click on the OK button to lock it in.
-
Repeat the process for the green and blue canvases. Don't worry if we don't get exactly the same intensity as the gnu. Close is good enough.
-
Now we combine our three canvases into one. Compose a new canvas (Filters -> Conversions -> Compose). For the R/H/C Image, specify our red canvas. For the G/S/M Image, specify the green. For the B/V/Y Image, specify the blue. (Ignore the fourth image setting, which is only used for CMYK composition.) When we click OK we'll see the result of all this work.
Section 3: Making 3D text
Now we combine the results of our first two sections to create 3D text on
our plaque surface. I learned this technique by reading one of Kai's Power
Tips that explained all about the wonders of PhotoShop (and GIMP) channel
operations.
-
We'll create two variations on our text canvas to create light and shadow effects. Begin by Offsetting (Alt-O) the text canvas from section 1 by -3,-2 pixels. Gaussian Blur (Alt-Shift-B) the new canvas by 3 pixels. Contrast Autostretch (Filters -> Map -> Contrast Autostretch) the result.
-
Subtract (Filters -> Channel Ops -> Subtract) the blurred canvas from the original text canvas. Invert the color of the result (Alt-I) to create a shadow above and to the left of the text.
-
Next we combine the shadow with our texture. Invert the color of the texture from section 2 (Alt-I), which gives us a weird orange effect. Multiply (Alt-M) the texture canvas by the shadow from the last step. Invert the result (Alt-I) to change back to the sky blue color and change the shadow to a highlight.
-
We do almost the same thing a second time to get the shadow. Offset (Alt-O) the text canvas, this time by +3,+2 pixels. Gaussian Blur (Alt-Shift-B) the new canvas by 3 pixels and Contrast Autostretch (Filters -> Map -> Contrast Autostretch) the result. Subtract (Filters -> Channel Ops -> Subtract) this canvas from the original text and Invert the color of the result (Alt-I). Multiply (Alt-M) this shadow by the canvas from step 3 to finish off our raised text.
All that's left is to put our gnu graphic in the right place and to round
off the corners of the plaque. We'll also think about the right format for
our final image in the Great GIF vs. JPEG debate.
documented on: 2007.01.23
