From 5a422aba704c375a307a902bafe658342e209906 Mon Sep 17 00:00:00 2001 From: scuri Date: Fri, 17 Oct 2008 06:10:15 +0000 Subject: First commit - moving from LuaForge to SourceForge --- html/en/rep_guide.html | 139 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 139 insertions(+) create mode 100644 html/en/rep_guide.html (limited to 'html/en/rep_guide.html') 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 @@ + + + + + + +Representation Guide + + + + + +

Image Representation Guide

+

Raw Data Buffer

+ +

To create a raw image buffer you can simply use the utility function:

+ +
+ 
int width, height, color_mode, data_type;
+int size = imImageDataSize(width, height, color_mode, data_type);
+void* buffer = malloc(size);
+
+ +
+

So if the data type is IM_FLOAT, we could write:

+
+ + 
float* idata = (float*)buffer;
+ +
+
+

Then to locate the pixel at line y, column x, component d simply write: +

+
+ + 
float value;
+if (is_packed) 
+value = idata[y*width*depth + x*depth + d]
+else
+value = idata[d*width*height + y*width + x]
+ +
+
+

But notice that this code will return values at different pixel locations for top down and bottom up + orientations.

+ +
+

imImage

+
+ +
+

To use the imImage structure you must include the <im_image.h> header.

+
+

To create an imImage structure you can do it in several ways:

+ +
+ + + 
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)
+ +

The imImageInit function allow you to initialize an imImage 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.

+

To destroy the imImage structure simply call imImageDestroy(image). If you do "data[0] + = NULL" before calling the destroy function then the raw data buffer will not be destroyed.

+ +
+ +
+

The imImage data buffer is allocated like the raw data buffer. +

+
+

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 + image->data[0] + contains a pointer to all the data, and image->data[1] is a short cut to the second component and so + on. With this you can use image->data[0] as a starting point for all the data, or use it as the first + component.

+ +
+ + + 
count = width*height;
+unsigned char* idata = (unsigned char*)image->data[0];
+for (int i = 0; i < count; i++)
+{
+  idata[i] = 255;
+}
+ +

or

+ + 
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;
+    }
+  }
+}
+ + +
+
+ +

The imImage 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 + IM_MAP images and + for pseudo color of IM_GRAY images.

+ +
+ +
+

An important subset of images is what we call a Bitmap image. It is an image that can be + directly used into the graphics display. For Bitmap images the color space must be + IM_RGB, IM_MAP, + IM_GRAY or IM_BINARY, and the data type must be IM_BYTE.

+
+

The conversion between image data types, color spaces and the conversion to bitmap are defined only + for the imImage structure.

+ + + + + -- cgit v1.2.3