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

Fields

Modifier and Type

Field

Description

protected boolean

autotransparent

autotransparency flag

protected boolean

closeStream

closeStream flag

protected int

colorDepth

number of bit planes

protected byte[]

colorTab

RGB palette

protected int

delay

frame delay

protected int

dispose

disposal code

protected boolean

firstFrame

first frame flag

protected byte[]

gct

global color table

protected int

GCTbl

blue color

protected int

GCTcindex

global color table index

protected boolean

GCTextracted

flag for extracting global color table

protected int

GCTgrn

green color

protected boolean

GCTloadedExternal

flag for global color table from external image

protected boolean

GCToverideColor

gct overide color flag

protected boolean

GCToverideIndex

gct overide index flag

protected int

GCTred

red color

protected boolean

GCTsetTransparent

gct transparency flag

protected boolean

gctused

use global color table flag

protected int

height

image height

protected ij.ImagePlus

image

current frame

protected byte[]

indexedPixels

converted frame indexed to palette

protected int

lctSize

local color table size

protected OutputStream

out

output stream

protected byte[]

pixels

BGR byte array from frame

protected int

repeat

repeat factor

static final int

REPEAT_FOREVER

Repeat forever flag

protected int

sample

default sample interval

protected boolean

sizeSet

set size flag

protected boolean

started

started flag

protected int

transIndex

transparency index

protected boolean

transparent

transparent flag

protected int

width

image width
Constructor Summary

Constructors

Constructor

Description

AnimatedGifEncoder()
Method Summary

Modifier and Type

Method

Description

boolean

addFrame(ij.ImagePlus image)

Adds next GIF frame.

boolean

addFrame(ij.ImagePlus image, int theDelay)

Adds next GIF frame.

protected void

analyzePixels()

Analyzes image colors and creates color map.

static void

createGif(OutputStream outputStream, Image image)

Create a GIF

static void

createGif(String filename, Image image)

Create a GIF

static void

createGif(String filename, List images)

Create an animated GIF

static void

createGif(String filename, List images, int repeat, int delay)

Create an animated GIF

static void

createGif(String filename, List images, int repeat, int delay, int endDelay)

Create an animated GIF

static void

createGif(String filename, List images, int repeat, int delay, int endDelay, boolean useGlobalTable)

Create an animated GIF

void

extractGCTrgb(ij.ImagePlus image)

Function to extract Global Color Table from RGB ImagePlus This function has to be called before addFrame

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)

Function to load Global Color Table from 8 bit ImagePlus This function has to be called before addFrame

void

loadGCTrgb(ij.ImagePlus image)

Function to use the first up to 255 elements of a RGB ImagePlus to construct a global color table.

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()

Set the options

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 Details
- REPEAT_FOREVER
  
  public static final int REPEAT_FOREVER
  
  Repeat forever flag
  See Also:
  
  Constant Field Values
- width
  
  protected int width
  
  image width
- height
  
  protected int height
  
  image height
- transparent
  
  protected boolean transparent
  
  transparent flag
- transIndex
  
  protected int transIndex
  
  transparency index
- repeat
  
  protected int repeat
  
  repeat factor
- delay
  
  protected int delay
  
  frame delay
- started
  
  protected boolean started
  
  started flag
- out
  
  protected OutputStream out
  
  output stream
- image
  
  protected ij.ImagePlus image
  
  current frame
- pixels
  
  protected byte[] pixels
  
  BGR byte array from frame
- indexedPixels
  
  protected byte[] indexedPixels
  
  converted frame indexed to palette
- colorDepth
  
  protected int colorDepth
  
  number of bit planes
- colorTab
  
  protected byte[] colorTab
  
  RGB palette
- lctSize
  
  protected int lctSize
  
  local color table size
- dispose
  
  protected int dispose
  
  disposal code
- closeStream
  
  protected boolean closeStream
  
  closeStream flag
- firstFrame
  
  protected boolean firstFrame
  
  first frame flag
- sizeSet
  
  protected boolean sizeSet
  
  set size flag
- sample
  
  protected int sample
  
  default sample interval
- gct
  
  protected byte[] gct
  
  global color table
- gctused
  
  protected boolean gctused
  
  use global color table flag
- autotransparent
  
  protected boolean autotransparent
  
  autotransparency flag
- GCTextracted
  
  protected boolean GCTextracted
  
  flag for extracting global color table
- GCTloadedExternal
  
  protected boolean GCTloadedExternal
  
  flag for global color table from external image
- GCTred
  
  protected int GCTred
  
  red color
- GCTgrn
  
  protected int GCTgrn
  
  green color
- GCTbl
  
  protected int GCTbl
  
  blue color
- GCTcindex
  
  protected int GCTcindex
  
  global color table index
- GCTsetTransparent
  
  protected boolean GCTsetTransparent
  
  gct transparency flag
- GCToverideIndex
  
  protected boolean GCToverideIndex
  
  gct overide index flag
- GCToverideColor
  
  protected boolean GCToverideColor
  
  gct overide color flag
Constructor Details
- AnimatedGifEncoder
  
  public AnimatedGifEncoder()
Method Details
- createGif
  
  public static void createGif(String filename, Image image)
  
  Create a GIF
  
  Parameters:
  
  filename - output file name
  
  image - the image object
- createGif
  
  public static void createGif(OutputStream outputStream, Image image)
  
  Create a GIF
  
  Parameters:
  
  outputStream - the output stream
  
  image - the image object
- createGif
  
  public static void createGif(String filename, List images)
  
  Create an animated GIF
  
  Parameters:
  
  filename - output file name
  
  images - list of images
- createGif
  
  public static void createGif(String filename, List images, int repeat, int delay)
  
  Create an animated GIF
  
  Parameters:
  
  filename - output file name
  
  images - list of images
  
  repeat - number of times to repeat
  
  delay - delay between images
- createGif
  
  public static void createGif(String filename, List images, int repeat, int delay, int endDelay)
  
  Create an animated GIF
  
  Parameters:
  
  filename - output file name
  
  images - list of images
  
  repeat - number of times to repeat
  
  delay - delay between images
  
  endDelay - delay on last image
- createGif
  
  public static void createGif(String filename, List images, int repeat, int delay, int endDelay, boolean useGlobalTable)
  
  Create an animated GIF
  
  Parameters:
  
  filename - output file name
  
  images - list of images
  
  repeat - number of times to repeat
  
  delay - delay between images
  
  endDelay - delay on last image
  
  useGlobalTable - true to use a global color table
- 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 - the image to add
  
  Returns:
  
  true if successful.
- addFrame
  
  public boolean addFrame(ij.ImagePlus image, int theDelay)
  
  Adds next GIF frame.
  
  Parameters:
  
  image - the image to add
  
  theDelay - delay in loop
  
  Returns:
  
  true if successful.
- setoptions
  
  public void setoptions()
  
  Set the options
- finish
  
  public boolean finish()
  
  Flushes any pending data and closes output file. If writing to an OutputStream, the stream is not closed.
  
  Returns:
  
  true if successful
- loadGCT8bit
  
  public void loadGCT8bit(ij.ImagePlus image)
  
  Function to load Global Color Table from 8 bit ImagePlus This function has to be called before addFrame
  
  Parameters:
  
  image - the image
- extractGCTrgb
  
  public void extractGCTrgb(ij.ImagePlus image)
  
  Function to extract Global Color Table from RGB ImagePlus This function has to be called before addFrame
  
  Parameters:
  
  image - the image
- loadGCTrgb
  
  public void loadGCTrgb(ij.ImagePlus image)
  
  Function to use the first up to 255 elements of a RGB ImagePlus to construct a global color table. This function has to be called before addFrame
  
  Parameters:
  
  image - the image
- setGCT
  
  public void setGCT(boolean flag)
  
  If gct = true then a global color table is use
  
  Parameters:
  
  flag - the gct flag
- 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 - the gtu flag
- 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 - the number of pixels
- 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 - the table
  
  r - red
  
  g - green
  
  b - blue
  
  Returns:
  
  the index
- writeGraphicCtrlExt
  
  protected void writeGraphicCtrlExt(int delay) throws IOException
  
  Writes Graphic Control Extension
  
  Parameters:
  
  delay - the delay
  
  Throws:
  
  IOException - problem writing
- writeImageDesc
  
  protected void writeImageDesc() throws IOException
  
  Writes Image Descriptor
  
  Throws:
  
  IOException - problem writing
- writeLSDgct
  
  protected void writeLSDgct() throws IOException
  
  Writes Logical Screen Descriptor with global color table
  
  Throws:
  
  IOException - problem writing
- writeLSD
  
  protected void writeLSD() throws IOException
  
  Writes Logical Screen Descriptor without global color table
  
  Throws:
  
  IOException - problem writing
- writeNetscapeExt
  
  protected void writeNetscapeExt() throws IOException
  
  Writes Netscape application extension to define repeat count.
  
  Throws:
  
  IOException - problem writing
- writePalette
  
  protected void writePalette() throws IOException
  
  Writes color table
  
  Throws:
  
  IOException - problem writing
- writePixels
  
  protected void writePixels() throws IOException
  
  Encodes and writes pixel data
  
  Throws:
  
  IOException - problem writing
- writeShort
  
  protected void writeShort(int value) throws IOException
  
  Write 16-bit value to output stream, LSB first
  
  Parameters:
  
  value - the value
  
  Throws:
  
  IOException - problem writing
- writeString
  
  protected void writeString(String s) throws IOException
  
  Writes string to output stream
  
  Parameters:
  
  s - the string
  
  Throws:
  
  IOException - problem writing

Class AnimatedGifEncoder

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Details

REPEAT_FOREVER

width

height

transparent

transIndex

repeat

delay

started

out

image

pixels

indexedPixels

colorDepth

colorTab

lctSize

dispose

closeStream

firstFrame

sizeSet

sample

gct

gctused

autotransparent

GCTextracted

GCTloadedExternal

GCTred

GCTgrn

GCTbl

GCTcindex

GCTsetTransparent

GCToverideIndex

GCToverideColor

Constructor Details

AnimatedGifEncoder

Method Details

createGif

createGif

createGif

createGif

createGif

createGif

addFrame

addFrame

setoptions

finish

loadGCT8bit

extractGCTrgb

loadGCTrgb

setGCT

setDelay

setDispose

setFrameRate

setQuality

GlobalColorTableused

setRepeat

setSize

setTransparent

start

start

OverRideQuality

analyzePixels

findClosest

writeGraphicCtrlExt

writeImageDesc

writeLSDgct

writeLSD

writeNetscapeExt

writePalette

writePixels

writeShort

writeString