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| author | scuri <scuri> | 2008-10-17 06:10:15 +0000 |
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| committer | scuri <scuri> | 2008-10-17 06:10:15 +0000 |
| commit | 5a422aba704c375a307a902bafe658342e209906 (patch) | |
| tree | 5005011e086bb863d8fb587ad3319bbec59b2447 /html/en/rep_guide.html | |
First commit - moving from LuaForge to SourceForge
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| -rw-r--r-- | html/en/rep_guide.html | 139 |
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diff --git a/html/en/rep_guide.html b/html/en/rep_guide.html new file mode 100644 index 0000000..0dfd939 --- /dev/null +++ b/html/en/rep_guide.html @@ -0,0 +1,139 @@ +<!doctype HTML PUBLIC "-//IETF//DTD HTML//EN"> +<html> + +<head> +<meta http-equiv="Content-Language" content="en-us"> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +<title>Representation Guide</title> +<link rel="stylesheet" type="text/css" href="../style.css"> +</head> + +<body> + +<h1>Image Representation Guide</h1> +<h3 align="left"><a name="raw">Raw Data Buffer</a></h3> + + <p align="left">To create a raw image buffer you can simply use the utility function:</p> + + <div align="left"> + <pre>int width, height, color_mode, data_type; +int size = imImageDataSize(width, height, color_mode, data_type); +void* buffer = malloc(size);</pre> + </div> + + <div align="left"> + <p align="left">So if the data type is <strong>IM_FLOAT</strong>, we could write:</div> + <div align="left"> + + <pre>float* idata = (float*)buffer;</pre> + + </div> + <div align="left"> + <p align="left">Then to locate the pixel at line y, column x, component d simply write: + </div> + <div align="left"> + + <pre>float value; +if (is_packed) +value = idata[y*width*depth + x*depth + d] +else +value = idata[d*width*height + y*width + x]</pre> + + </div> + <div align="left"> + <p align="left">But notice that this code will return values at different pixel locations for top down and bottom up + orientations.</div> + +<div align="left"> + <h3 align="left"><a name="imImage">imImage</a></h3> +</div> + + <div align="left"> + <p align="left">To use the <b>imImage</b> structure you must include the <im_image.h> header.</div> + <div align="left"> + <p align="left">To create an <b>imImage</b> structure you can do it in several ways:</div> + +<div align="left"> + + + <pre>int width, height, color_space, data_type, palette_count; +long *palette; +void* buffer + +imImage* image; + +image = imImageCreate(width, height, color_space, data_type) +image = imImageInit(width, height, color_space, data_type, buffer, palette, palette_count) +image = imImageDuplicate(image) +image = imImageClone(image) </pre> + + <p>The <b>imImageInit</b> function allow you to initialize an <b>imImage</b> structure with an user allocated + buffer. This is very useful if you use your own image structure and wants to temporally use the image processing + functions of the library.</p> + <p>To destroy the <b>imImage</b> structure simply call <b>imImageDestroy(image)</b>. If you do "<b>data[0] + = NULL</b>" before calling the destroy function then the raw data buffer will not be destroyed.</p> + +</div> + + <div align="left"> + <p align="left">The <b>imImage</b> data buffer is allocated like the raw data buffer. + </div> + <div align="left"> + <p align="left">The separated color components are arranged one after another, but we access the data through an + array of pointers each one starting at the beginning of each color component. So + <b>image->data[0]</b> + contains a pointer to all the data, and <b>image->data[1]</b> is a short cut to the second component and so + on. With this you can use <b>image->data[0]</b> as a starting point for all the data, or use it as the first + component.</div> + +<div align="left"> + + + <pre>count = width*height; +unsigned char* idata = (unsigned char*)image->data[0]; +for (int i = 0; i < count; i++) +{ + idata[i] = 255; +}</pre> + + <p>or</p> + + <pre>for (int d = 0; d < image->depth; d++) +{ + unsigned char* idata = (unsigned char*)image->data[d]; + + for (int y = 0; y < height; y++) + { + for (int x = 0; x < width; x++) + { + int offset = y * width + x; + + idata[offset] = 255; + } + } +}</pre> + + +</div> +<div align="left"> + + <p align="left">The <b>imImage</b> structure contains all the image information obtained from a file, because it + also has support for alpha, attributes and the palette. The palette can be used for + <b>IM_MAP</b> images and + for pseudo color of <b>IM_GRAY</b> images.</p> + +</div> + + <div align="left"> + <p align="left">An important subset of images is what we call a <b>Bitmap</b> image. It is an image that can be + directly used into the graphics display. For Bitmap images the color space must be + <b>IM_RGB</b>, <b>IM_MAP</b>, + <b>IM_GRAY</b> or <b>IM_BINARY</b>, and the data type must be <b>IM_BYTE</b>.</div> + <div align="left"> + <p align="left">The conversion between image data types, color spaces and the conversion to bitmap are defined only + for the <b>imImage</b> structure.</div> + + +</body> + +</html> |