- Uploading a BlendGIF option file
- There are two ways of specifying your animated GIF:
- By using the fields on this form to choose options
- By uploading a special BlendGIF input file
The second option requires that you create an ascii (text) file on your machine,
and enter it's name in the Upload load options from a file field.
This file should contain a list of option names, and their values.
For example:
INFILE.0=2
INFILE.1=http://www.images.org/image1.gif
INFILE.2=http://manysites.net/~me/myface.gif
ANIM_TYPE=BALLOON
BALLOON_TYPE=CIRCLE
BALLOON_PUSH=OVERWRITE
For details on parameter names, please see the
BlendGIF manual
- The list of GIF images to "blend"
- You can specify up to 7 images to "blend". You can also
select which "frame", in an animated GIF, to use.
Notes:
- you can enter a file name or a URL
- URLs must start with http://
- Filenames are relative to this server's
()
"BlendGif" directory
- BLENDGIF will use socket calls to retrieve URLS.
The content returned from the server must have a
content-type response header of image/gif.
- the file must be a GIF file (BMP, JPEG,
etc. will not be read).
- the size of the animated gif is set by the
Size of image option
(with possible modifications via the
image-specific transformations)
- Advanced option: Instead of a server-file or a URL,
you can upload your own GIF files
- Image number
- This image number refers to a frame within an animated gif -- this
option allows you to pluck one of the frames from a pre-existing animated GIF .
If the GIF file you wish to use is not an animated GIF, the image number is
ignored (since there is only one image to choose from).
- Number of times to display the set of images
- Iterations should be an integer greater then 0.
- Delay between frames
- In 1/100th seconds. Thus, a value of 50 means 1/2 second.
- Number of frames between each image pair
- More frames means smoother transitions, but also means larger files
and longer processing time.
- Cycle images back to first image
- You can create a "cyclical" animated GIF, with the display of
intermediate images reversed. This is a nice way of smoothing
repeated displays, you avoid discontinuous jumps between the last
and first image.
Alternatively, one could specify a sequence of
images that start with a first image, have the "last" image in
the middle, and end with the first image -- but that doubles
the processing time required.
- Setting the size of the image
- There are three choices:
The Width and height fields are only used when the
Specify a width and height option is chosen (otherwise, they
are ignored).
In addition to this automatic size computation, you can
specify image-specific transformations.
- Attempt to minimize the size of the final GIF file
- By default, BlendGIF uses a fairly inefficient method of storing image
information: each frame contains a complete image. That is, each frame of
the animated GIF "covers" the full width and height of the image. Since in
many cases only a fraction of the pixels change between frames, the size of the
final image ile can be substantially reduced by using
"retain prior image" features of the GIF standard.
You can instruct BlendGIF to attempt to shrink the file size (using
this retain prior image trick). This requires an additional step, which
is attempted after all frames have been computed (hence, it requires
additional processing time).
Caution: the results of this "shrinkage" may cause some browsers to crash!
- Immediately upload image
- After BlendGIF constructs your animated GIF, it can either:
- Immediately transfer it to you.
This requires a browser that suports maintained
connections
- Do not immediately transfer the image.
Instead, save it as a temporary file, which you can then obtain (by
clicking on a link).
If you want to save your results, use this option
Note that the temporary file will be retained (on this
server) for a short time period.
- Stop after this many frames
- Instead of creating all the frames, stop after you've drawn
this many framees. This can create some interesting
partial replacements, especially when combined with
the cycle-back option.
To suppress this trick (that is, to display all the frames),
leave this field blank.
- Suppress transparency
- If selected then either:
When not explicitly disabled, transparency is based on
whether the specified images were transparent.
In some cases, transparency seems to cause odd problems, which can
be solved by enabling this option.
In other cases, enabling transparency can improve the image (as when
trying to add images to pre-existing images).
- Set the accuracy of "best fades"
-
Processing fades requires matching colors determined on the fly to
a color in the global color table. To expedite this process, a 3
dimensional index is created. You can set the size of this
index -- larger values tend to yield smoother fades, but can greatly
increase processing time.
The default value (16) seems to be a reasonable
compromise between speed and quality.
- Image disposal
- How to dispose of images. When using
automatic resizing this parameter
may have little effect. However, when using image-specific
transformations,
this can have a major impact (on whether prior images are retained or erased).
- Colors in merged color table
- The length of the "global" color table
BlendGif will create a combined color table using all the
images you specify. This "global" color table is used
to display the intermediate images.
Note that the original images will be displayed with
their own "local" color table.
- Merge color table by
-
It's quite possible that the combined number of colors
(in the merged color table) is
greater then 256 (256 is the maximum number of colors a GIF can
use),
In such cases, BlendGif will need to pick and choose which colors to use.
CT_MAKE_SPEC is used to select from three different methods:
- use the most frequent colors
- use the most frequent colors, but also use some "average"
colors (these are chosen to minimize the "distance" of
all colors in all images to the closest color in the global color
table.
- similar to 2, but create more of the "average" colors.
Method 1 is fastest, but may do a bad job of displaying infrequently
used colors. Methods 2 and 3 provide some insurance against this
problem, but are slower.
- Background colors
- These values are used for pixel 0. This color is
used when you've selected no resizing of images, and an image
is smaller then a user specified height and width.
Note that Pixel 0 is displayed when transparency is turned off.
You should enter a value between 0 and 255 (inclusive) -- where 0 is "no color"
and 255 is "maxiumum brightness".
ADD |
The second image is added on top of the first image.
Intermediate frames are not created --
the second image simply is placed on top of the first image.
| If you want to retain portions of the first image, so as to
"sequentially build" a final image, you can:
- Use transformed images
- use images that have a lot of transparent pixels, in connjunction
with the do not suppress transparency
and the retain disposal options.
- Special Note:
You can create a moving-series of images
(across a constant
background) by using a series of values for
when specifying image-specific transformations
|
BALLOON |
The first image is replaced by an expanding "balloon"
of the second image.
|
Four balloon types are recognized:
- SQUARE: A square balloon
- DIAMOND: A diamond balloon
- OCTAGON: An octagon balloon
- CIRCLE: A circular balloon.
|
Three overwrite modes are available:
- OVERWRITE: second image overwrites first image
- PUSH: second image "pushes" first image "off the screen".
- SQUOOSH: second image "squooshes" the first image "into oblivion".
|
CURTAIN |
The second image is a curtain pulled over the first image |
- Two fractions (between 0 and 1) are used locate the center of the
balloon.
- There are three choices for which direction to draw the curtain:
- Top to bottom
- Left to right
- Two curtains converging in the middle (from left and right)
|
Three overwrite modes are available:
- OVERWRITE: second image overwrites first image
- PUSH: second image "pushes" first image "off the screen"
- SQUOOSH: second image "squooshes" first image "into oblivion"
|
DISSOLVE |
The first image dissolves into the second image
|
DISSOLVE works by randomly replacing image1 pixels with image2
pixels; with latter frames containing a greater proportion of
image2 pixels.
You can customize the speed of the dissolve by modifying the dissolve speed.
This parameter should contain a space delimited list of integers
between 0 (0 percent-- use image 1 pixels) to 100 (100 percent --
use image 2 pixels). These values are used to
create a graph, with each frames "dissolve threshold" read
from the graph.
Examples:
- 1 = a linear ramp (starting from 0 to 100)
- 1 10 80 90 = start with a slow change, a quick jump, ending with a slow change
|
FADE |
The first image fades into the second image. |
There are several ways of specifying a fade:
|
MASK |
"Mask" files are used to overlay portions of the second image
onto the first image.
|
If a pixel value in a mask file pixel value is greater then
0, then the corresponding pixel in image 1 (the one at the same row
and column position) is replaced with the corresponding image 2 pixel.
Note that the mask files are either replicated or
clipped to assure that their size corresponds to the size of the first
image.
|