Programming PHP

many colors as you need. The latter are known as true color formats, because 24-bit
color (8 bits for each of red, green, and blue) gives more hues than the human eye
can distinguish.
Creating and Drawing Images
For now, let’s start with the simplest possible GD example. Example 9-1 is a script
that generates a black filled square. The code works with any version of GD that supports
the PNG image format.
Example 9-1. A black square on a white background (black.php)
Example 9-1 illustrates the basic steps in generating any image: creating the image,
allocating colors, drawing the image, and then saving or sending the image.
Figure 9-1 shows the output of Example 9-1.
Figure 9-1. A black square on a white background
To see the result, simply point your browser at the black.php PHP page. To embed
this image in a web page, use:
The Structure of a Graphics Program
Most dynamic image-generation programs followthe same basic steps outlined in
Example 9-1.
You can create a 256-color image with the ImageCreate( ) function, which returns an
image handle:
$image = ImageCreate(width, height);
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