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/storage.html | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 html/en/storage.html (limited to 'html/en/storage.html') diff --git a/html/en/storage.html b/html/en/storage.html new file mode 100644 index 0000000..138d539 --- /dev/null +++ b/html/en/storage.html @@ -0,0 +1,72 @@ + + + + + +Storage + + + + + +

Storage Overview

+ +

Essentially all the file formats save the same image data. There is no such + thing like a GIF image, instead we have a color indexed image that can be + saved in a file with a GIF format, or a TIFF format, etc. However the + compression encoding can be lossy and degrade the original image. The point is + file formats and image data are two different things.

+

A file format is a file organization of the image data and its attributes. + The IM library model considers all the file formats under the same model, + including image, video, animation, stacks and volume file formats. When there + is more than one image each one is treated as an independent frame. Each frame + can have its own parameters and set of attributes.

+

The abstract model we use has the following structure:

+
+
+ + + + + + + + + + + + + + + + + + + + + + + + + +
Format Identifier
Compression
Image Count
+ Image Information:
+ parameters, attributes, palette
Image Data
Image Information:
+ parameters, attributes, palette
Image Data
...
+
+
+

The compression is usually the same for all the images in the file, but it + can be changed after loading an image. For tradicional file formats image + count is always 1. Image information must always be loaded or saved before + image data.

+

We consider only formats that starts with a signature so we can recognize + the format without using its file extension. If there is more than one driver + that handles the same signature the first registered driver will open the + file. Since the internal drivers are automatically registered all the external + drivers can be loaded first if no imFile function has been called. In + this way you can also control which external driver goes first.

+ + + + + -- cgit v1.2.3