ucar.unidata.ui
Class AnimatedGifEncoder

java.lang.Object
  ucar.unidata.ui.AnimatedGifEncoder

public class AnimatedGifEncoder
extends Object

Class AnimatedGifEncoder - Encodes a GIF file consisting of one or more frames.

 Extensively Modified for ImagePlus
 Extended to handle 8 bit Images with more complex Color lookup tables with transparency index

 Ryan Raz March 2002
 raz@rraz.ca
 Version 1.01
 Extensively Modified for ImagePlus
 Extended to handle 8 bit Images with more complex Color lookup tables with transparency index

 Ryan Raz March 2002
 ryan@rraz.ca
 Version 1.01 Please report any bugs

 Operation Manual


 1) Load stack with 8 bit or RGB images it is possible to use the animated gif reader but because the color
   table is lost it is best to also load a separate copy of the first image in the series this will allow
   extraction of the original image color look up table (see 1below)
 2)Check the option list to bring up the option list.
 3)Experiment with the option list. I usually use a global color table to save space, set to do not dispose if
      each consecutive image is overlayed on the previous image.
 4)Color table can be imported from another image or extracted from 8bit stack images or loaded as the
    first 256  RGB triplets from a RGB images, the last mode takes either a imported image or current
    stack and creates the color table from scratch.


    To do list

     1) Modify existing Animated Gif reader plug in to import in 8 bit mode (currently only works in
         RGB  mode.  Right now the best way to alter an animated gif is to save the first image separately
         and then read the single gif and use the plugin animated reader to read the animated gif to the
         stack. Let this plugin encode the stack using the single gif's color table.
      2) Add support for background colors easy but I have no use for them
      3) RGB to 8 bit converter is a linear search. Needs to be replaced with sorted list and fast search. But
          this update could cause problems with some types of gifs. Easy fix get a faster computer.
      4) Try updating NN color converter seems to be heavily weighted towards quantity of pixels.
        example:
           if there is 90% of the image covered in shades of one color or grey the 10% of other colors tend
           to be poorly represented it  over fits the shades and under fits the others. Works well if the
          distribution  is balanced.
       5) Add support for all sizes of Color Look Up tables.
       6) Re-code to be cleaner. This is my second Java program and I started with some code with too
           many  global variables and I added more switches so its a bit hard to follow.

 Credits for the base conversion codes
 No copyright asserted on the source code of this class.  May be used
 for any purpose, however, refer to the Unisys LZW patent for restrictions
 on use of the associated LZWEncoder class.  Please forward any corrections
 to kweiner@fmsware.com.




Version:
  
1.0 December 2000


 Example:
    AnimatedGifEncoder e = new AnimatedGifEncoder();
    e.start(outputFileName);
    e.addFrame(image1);
    e.addFrame(image2);
      "           "             "
    e.finish();
 

Author:

Kevin Weiner, FM Software

Field Summary

protected boolean	autotransparent _more_
protected boolean	closeStream _more_
protected int	colorDepth _more_
protected byte[]	colorTab _more_
protected int	delay _more_
protected int	dispose _more_
protected boolean	firstFrame _more_
protected byte[]	gct _more_
protected int	GCTbl _more_
protected int	GCTcindex _more_
protected boolean	GCTextracted _more_
protected int	GCTgrn _more_
protected boolean	GCTloadedExternal _more_
protected boolean	GCToverideColor _more_
protected boolean	GCToverideIndex _more_
protected int	GCTred _more_
protected boolean	GCTsetTransparent _more_
protected boolean	gctused _more_
protected int	height _more_
protected ij.ImagePlus	image _more_
protected byte[]	indexedPixels _more_
protected int	lctSize _more_
protected OutputStream	out _more_
protected byte[]	pixels _more_
protected int	repeat _more_
static int	REPEAT_FOREVER _more_
protected int	sample _more_
protected boolean	sizeSet _more_
protected boolean	started _more_
protected int	transIndex _more_
protected boolean	transparent _more_
protected int	width _more_

Constructor Summary

AnimatedGifEncoder()

Method Summary

boolean	addFrame(ij.ImagePlus image) Adds next GIF frame.
boolean	addFrame(ij.ImagePlus image, int theDelay) _more_
protected void	analyzePixels() Analyzes image colors and creates color map.
static void	createGif(OutputStream outputStream, Image image) _more_
static void	createGif(String filename, Image image) _more_
static void	createGif(String filename, List images) _more_
static void	createGif(String filename, List images, int repeat, int delay) _more_
void	extractGCTrgb(ij.ImagePlus image) _more_
protected int	findClosest(byte[] colorTab, int r, int g, int b) Returns index of palette color closest to c
boolean	finish() Flushes any pending data and closes output file.
void	GlobalColorTableused(boolean gtu) Set True for Global Color Table use This saves space in the output file but colors may not be so goodif the stack uses True color images
void	loadGCT8bit(ij.ImagePlus image) _more_
void	loadGCTrgb(ij.ImagePlus image) _more_
void	OverRideQuality(int npixs) Sets Net sample size depending on image size
void	setDelay(int ms) Sets the delay time between each frame, or changes it for subsequent frames (applies to last frame added).
void	setDispose(int code) Sets the GIF frame disposal code for the last added frame and any subsequent frames.
void	setFrameRate(float fps) Sets frame rate in frames per second.
void	setGCT(boolean flag) If gct = true then a global color table is use
void	setoptions() _more_
void	setQuality(int quality) Sets quality of color quantization (conversion of images to the maximum 256 colors allowed by the GIF specification).
void	setRepeat(int iter) Sets the number of times the set of GIF frames should be played.
void	setSize(int w, int h) Sets the GIF frame size.
void	setTransparent(boolean c) Sets the transparent color for the last added frame and any subsequent frames.
boolean	start(OutputStream os) Initiates GIF file creation on the given stream.
boolean	start(String file) Initiates writing of a GIF file with the specified name.
protected void	writeGraphicCtrlExt(int delay) Writes Graphic Control Extension
protected void	writeImageDesc() Writes Image Descriptor
protected void	writeLSD() Writes Logical Screen Descriptor without global color table
protected void	writeLSDgct() Writes Logical Screen Descriptor with global color table
protected void	writeNetscapeExt() Writes Netscape application extension to define repeat count.
protected void	writePalette() Writes color table
protected void	writePixels() Encodes and writes pixel data
protected void	writeShort(int value) Write 16-bit value to output stream, LSB first
protected void	writeString(String s) Writes string to output stream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

REPEAT_FOREVER

public static final int REPEAT_FOREVER

_more_

See Also:

Constant Field Values

width

protected int width

_more_

height

protected int height

_more_

transparent

protected boolean transparent

_more_

transIndex

protected int transIndex

_more_

repeat

protected int repeat

_more_

delay

protected int delay

_more_

started

protected boolean started

_more_

out

protected OutputStream out

_more_

image

protected ij.ImagePlus image

_more_

pixels

protected byte[] pixels

_more_

indexedPixels

protected byte[] indexedPixels

_more_

colorDepth

protected int colorDepth

_more_

colorTab

protected byte[] colorTab

_more_

lctSize

protected int lctSize

_more_

dispose

protected int dispose

_more_

closeStream

protected boolean closeStream

_more_

firstFrame

protected boolean firstFrame

_more_

sizeSet

protected boolean sizeSet

_more_

sample

protected int sample

_more_

gct

protected byte[] gct

_more_

gctused

protected boolean gctused

_more_

autotransparent

protected boolean autotransparent

_more_

GCTextracted

protected boolean GCTextracted

_more_

GCTloadedExternal

protected boolean GCTloadedExternal

_more_

GCTred

protected int GCTred

_more_

GCTgrn

protected int GCTgrn

_more_

GCTbl

protected int GCTbl

_more_

GCTcindex

protected int GCTcindex

_more_

GCTsetTransparent

protected boolean GCTsetTransparent

_more_

GCToverideIndex

protected boolean GCToverideIndex

_more_

GCToverideColor

protected boolean GCToverideColor

_more_

Constructor Detail

AnimatedGifEncoder

public AnimatedGifEncoder()

Method Detail

createGif

public static void createGif(String filename,
                             Image image)

_more_

Parameters:

filename - _more_

image - _more_

createGif

public static void createGif(OutputStream outputStream,
                             Image image)

_more_

Parameters:

outputStream -

image - _more_

createGif

public static void createGif(String filename,
                             List images)

_more_

Parameters:

filename - _more_

images - _more_

createGif

public static void createGif(String filename,
                             List images,
                             int repeat,
                             int delay)

_more_

Parameters:

filename - _more_

images - _more_

repeat - _more_

delay - _more_

addFrame

public boolean addFrame(ij.ImagePlus image)

Adds next GIF frame. The frame is not written immediately, but is actually deferred until the next frame is received so that timing data can be inserted. Invoking finish() flushes all frames. If setSize was not invoked, the size of the first image is used for all subsequent frames.

Parameters:

image - _more_

Returns:

true if successful.

addFrame

public boolean addFrame(ij.ImagePlus image,
                        int theDelay)

_more_

Parameters:

image - _more_

theDelay - _more_

Returns:

_more_

setoptions

public void setoptions()

_more_

finish

public boolean finish()

Flushes any pending data and closes output file. If writing to an OutputStream, the stream is not closed.

Returns:

_more_

loadGCT8bit

public void loadGCT8bit(ij.ImagePlus image)

_more_

Parameters:

image - _more_

extractGCTrgb

public void extractGCTrgb(ij.ImagePlus image)

_more_

Parameters:

image - _more_

loadGCTrgb

public void loadGCTrgb(ij.ImagePlus image)

_more_

Parameters:

image - _more_

setGCT

public void setGCT(boolean flag)

If gct = true then a global color table is use

Parameters:

flag - _more_

setDelay

public void setDelay(int ms)

Sets the delay time between each frame, or changes it for subsequent frames (applies to last frame added).

Parameters:

ms - int delay time in milliseconds

setDispose

public void setDispose(int code)

Sets the GIF frame disposal code for the last added frame and any subsequent frames. Default is 0 if no transparent color has been set, otherwise 2.

Parameters:

code - int disposal code.

setFrameRate

public void setFrameRate(float fps)

Sets frame rate in frames per second. Equivalent to setDelay(1000/fps).

Parameters:

fps - float frame rate (frames per second)

setQuality

public void setQuality(int quality)

Sets quality of color quantization (conversion of images to the maximum 256 colors allowed by the GIF specification). Lower values (minimum = 1) produce better colors, but slow processing significantly. 10 is the default, and produces good color mapping at reasonable speeds. Values greater than 20 do not yield significant improvements in speed.

Parameters:

quality - int greater than 0.

GlobalColorTableused

public void GlobalColorTableused(boolean gtu)

Set True for Global Color Table use This saves space in the output file but colors may not be so goodif the stack uses True color images

Parameters:

gtu - _more_

setRepeat

public void setRepeat(int iter)

Sets the number of times the set of GIF frames should be played. Default is 1; 0 means play indefinitely. Must be invoked before the first image is added.

Parameters:

iter - int number of iterations.

setSize

public void setSize(int w,
                    int h)

Sets the GIF frame size. The default size is the size of the first frame added if this method is not invoked.

Parameters:

w - int frame width.

h - int frame width.

setTransparent

public void setTransparent(boolean c)

Sets the transparent color for the last added frame and any subsequent frames. Since all colors are subject to modification in the quantization process, the color in the final palette for each frame closest to the given color becomes the transparent color for that frame. May be set to null to indicate no transparent color.

Parameters:

c - Color to be treated as transparent on display.

start

public boolean start(OutputStream os)

Initiates GIF file creation on the given stream. The stream is not closed automatically.

Parameters:

os - OutputStream on which GIF images are written.

Returns:

false if initial write failed.

start

public boolean start(String file)

Initiates writing of a GIF file with the specified name.

Parameters:

file - String containing output file name.

Returns:

false if open or initial write failed.

OverRideQuality

public void OverRideQuality(int npixs)

Sets Net sample size depending on image size

Parameters:

npixs - _more_

analyzePixels

protected void analyzePixels()

Analyzes image colors and creates color map.

findClosest

protected int findClosest(byte[] colorTab,
                          int r,
                          int g,
                          int b)

Returns index of palette color closest to c

Parameters:

colorTab - _more_

r - _more_

g - _more_

b - _more_

Returns:

_more_

writeGraphicCtrlExt

protected void writeGraphicCtrlExt(int delay)
                            throws IOException

Writes Graphic Control Extension

Parameters:

delay - _more_

Throws:

IOException - _more_

writeImageDesc

protected void writeImageDesc()
                       throws IOException

Writes Image Descriptor

Throws:

IOException - _more_

writeLSDgct

protected void writeLSDgct()
                    throws IOException

Writes Logical Screen Descriptor with global color table

Throws:

IOException - _more_

writeLSD

protected void writeLSD()
                 throws IOException

Writes Logical Screen Descriptor without global color table

Throws:

IOException - _more_

writeNetscapeExt

protected void writeNetscapeExt()
                         throws IOException

Writes Netscape application extension to define repeat count.

Throws:

IOException - _more_

writePalette

protected void writePalette()
                     throws IOException

Writes color table

Throws:

IOException - _more_

writePixels

protected void writePixels()
                    throws IOException

Encodes and writes pixel data

Throws:

IOException - _more_

writeShort

protected void writeShort(int value)
                   throws IOException

Write 16-bit value to output stream, LSB first

Parameters:

value - _more_

Throws:

IOException - _more_

writeString

protected void writeString(String s)
                    throws IOException

Writes string to output stream

Parameters:

s - _more_

Throws:

IOException - _more_