DroGIF Tutorial

updated 97.06.12 at 4:30PM MST

[ Tutorial 1 ] [ Tutorial 2 ] [ Tutorial 3 ] [ CFG file format ] [ FAQ ]

Tutorial 1

The bowl above was contructed in about 15 minutes using SuperPaint, PhotoShop, and DroGIF.

When I did the bowl animation, the first thing to decide was how many frames I wanted. The more frames, the smoother the motion, but also the larger the GIF's size. I laid out a series of six frames in SuperPaint, 32 pixels high by 32 pixels wide. I drew the basic bowl, then copied it to each of the six frames. The bubbles were then added. Here is the result:

The first frame has no bubbles. A good rule of thumb is to put all important information in the first frame, since some viewers (web browsers) cannot display animated GIFs, just the first image.

After I had the frames, I cut and paste the whole block of six images into a new Photoshop document. The reason was to ease the chore of constructing an indexed color table. The images were pasted; I had an RGB image and color table. A GIF only supports 256 colors in an indexed color table. To get this, I just change the color mode from RGB to indexed and Photoshop generates the indexed table. The resulting table applies to each individual frame. This is useful if you want one global color table, as opposed to each image having its own (and that takes up more space.)

After creating the indexed color table, I saved the file as a GIF, since it was to be my template for any future changes. I then repeatedly used this template to crop and save each of the six frames individually.

I quit Photoshop and opened the DroGIF.CFG file with SimpleText. I changed the settings to be as follows:

     FILENAME=bowl.gif
     ONECTAB=YES
     DELAY=25
     LOOP=YES

I saved the CFG file and quit SimpleText. From the Finder I selected the six frames named 'frame1.gif' through 'frame6.gif'.

I then dragged them over the DroGIF application. The bowl.gif file appeared, and I was done!

Please note, in the v1.0 DEMO, the config file must be in the same folder as the application (as shown in the above screenshot.)

So remember:

more frames for smoother animation

fewer frames for smaller GIFs (decreased download time)

contruct your frames on one document to share a color table

first frame should express important content

Tutorial 2

Like the first tutorial, I drew the images in SuperPaint and used Photoshop to make the indexed color tables. However, instead of using 'save' from within Photoshop, I used the 'export' feature with 'GIF89a'. Photoshop (3.0) does not let you define transparency for GIF through normal 'save'; so you use export to define which color in the table is your transparent one. When I want transparency, I pick a color I know I won't use (like hot pink) for the background. I then select this color to be transparent through the GIF export facility.

The configuration file for these images is special because of the DISPMETH command in the configuration file. When the viewer (browser) draws GIF images onto the screen, there are effectively three defined behaviors.

don't erase the background (DISPMETH=0 or 1)

erase the background with a default background color (DISPMETH=2)

restore the background with whatever was there before drawing(DISPMETH=3)

If you use transparency, make sure you use a value of 2 or 3 for DISPMETH! Also beware of using hilite colors (like black or white) for transparency.

Tutorial 3

DroGIF accepts PICT files as well as GIF. PICT files are the standard graphics format for Macintosh. They can include 2, 4, 8, 16, or 32 bit images using indexed or RGB color tables, and with QuickTime they can be compressed (i.e.JPG)! They may also include graphics primitives and text instead of bitmaps. Lost yet? Don't worry. With DroGIF and QuickTime installed, dragging any PICT documents onto the DroGIF application will automatically convert them into GIF format. You can mix and match PICT and GIF files. The only restriction is the first image area be larger than or equal to the following images. ONECTAB should be set to NO (the default), unless you are REALLY certain all your images have the same color table (which is guaranteed if you set ALWAYS256 to YES). The above image is cycling through the various DITHER options.

Configuration File Format

Although the following keywords can be in any order, there must be one per line. Do not put white space before or after a keyword. You can have anything after the '=' character.

FILENAME=<filename>

FILENAME allows you to specify the filename of the created GIF. It can be up to 27 characters long, containing no colons. (Default is 'DroGIF Out'.)

ONECTAB=[YES,NO] (Disabled in DEMO.)

ONECTAB can be set to YES or NO. If set to NO, individual GIFs global color tables become local color tables in the image stream. This is the safest setting. If set to YES, the first GIFs global color table is used for all images. If not use correctly (for example, if you don't use the same indexed palette in all your GIFs) you will get strange color mappings. Use with caution. (Default is NO.)

DELAY=[0..65535]

Setting DELAY to 0 will have no delay between presentation of the images. A non-zero value N will introduce a delay of N/100 seconds for each image. (Default is 0.)

COMMENT=<string> (Disabled in DEMO.)

You can include a 254 character 7 bit ASCII string to be included somewhere in the animated GIF. (Default is OMDI ©.)

LOOP=[YES,NO]

By setting LOOP to YES, the animation will loop repeatedly with browsers like Netscape Navigator. (Default is NO.)

DISPMETH=[0..3]

Tells the fewer how to deal with images in the GIF. (Default is 0.)
0 - no special action
1 - leave graphic in place
2 - restore background color
3 - restore previous contents

STRIP=[YES,NO] (Disabled in DEMO.)

Remove embedded comment blocks (but not the one set by COMMENT.) (Default is NO.)

INTERLACE=[YES,NO]

Make PICT image interlaced GIF if set to yes. Mom says "they load like venetian blinds" if interlaced. (Default is NO.)

ALWAYS256=[YES,NO]

Force PICT images to always use the system 256 color table. Useful for compressed images that lie about the number of colors they express themselves in. Recommend (safe) to use ONECTAB with this option. Requires QuickTime. (Default is NO.)

DITHER=[0..2]

Dithering settings for >8 bit PICT images. Requires QuickTime. (Default is 2.)
0 - do not dither
1 - dither
2 - color match

TRANSCOLOR=[0..255],[0..255],[0..255] (Disabled in DEMO.)

Mark the color noted as transparent. (Default is none.)

TRANSIDX=[0..255] (Disabled in DEMO.)

Mark the color index noted as transparent. (Default is none.)

Frequently Asked Questions

Why don't you have a preferences dialog instead of a configuration file?
The reason why I did not add a preferences dialog is for the most part I will not be changing my configuration and I like the convenience of drag, drop, and quit.

Can I drag disks and folders onto the DroGIF application?
Yes, but there is no promise the images will be ordered as you might expect. Its okay for just flipping ads, but not animation.

Is the order in which I select GIFs important?
Yes. They are ordered in the output file in the order you select them.

Can I use already animated GIFs?
Yes. But their graphic control block is replaced with DroGIF's. I make an attempt to keep transparency information, and if an image already has a local color table I use it. The existing image blocks (with position) information are preserved.

Can I use images that aren't the same size?
Yes... but the first image should enclose all the smaller images. If not, you will find a nasty bug in Netscape Navigator (3). Explorer works just fine.

What happens if there is an error?
Throw away the output GIF and look at the DroGIF.TXT file for specific error messages. This file should be of zero length. If you can't figure out what the error is, send me mail containing the DroGIF.TXT file.

When I drag the DroGIF.CFG file with the .GIF files with the DEMO, I get wierd errors.
Yes, this feature was disabled in the 0.9 DEMO, and has manifested itself as a bug in the 1.0 DEMO. It doesn't happen in the registered copy, and I will post a new DEMO soon. Another bug in the DEMO was generated by DELAY > 255.

Why don't you make optimal color tables for images with more than 8 bits color?
Use Photoshop.

Do I need QuickTime to run DroGIF?
No. DroGIF plus only calls QuickTime if ALWAYS256=YES, or if it needs to convert a compressed (JPG etc.) image, or any image with more than 256 colors.

Why do some JPEG images with DroGIF come out as black and white?
Some PICT images do not return correct color information. If this happens to you, set ALWAYS256=YES. This will use the system color table instead of the bad mojos in some PICT files.

Are there Windows versions of SpliGIF or DroGIF?
No. Drag and drop doesn't work the same way under Windows.

Can I have multiple config files to change delays between images?
Yes, if they are named/selected appropriately. The CFG files should be selected before the image it modifies. Example:

image1.cfg image1.gif image2.cfg image2.gif imageN.cfg imageN.gif