Instructions

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Installing  ColorRamp

Copy the ColorRamp extension file (ColorRamp.avx) into your EXT32 folder.  By default, this is /ESRI/Av_Gis30/ArcView/Ext32.  (For those of you with custom installations: relative to the folder where the ArcView executable program  is installed, this is ../Ext32)

Loading ColorRamp

To make ColorRamp available within an ArcView project, choose the ColorRamp extension from the Project|Extensions or View|File|Extensions dialog by checking the box next to it.

ColorRamp will install this button on the right hand side of your view button bar.  It will be disabled until you have an active theme in your view.

Using ColorRamp

Pressing the button brings up the ColorRamp dialog.  This dialog can be moved aside, even beyond ArcView's window, so you can see your work.  In short, it functions a lot like the usual legend editor, with which it can coexist.

The basic operation to follow is this.

  1. First choose the theme.  If you have not already done so, use the ArcView legend editor to choose the field to display, how to display it (graduated colors is probably best, but unique value works fine too), and how many classes to use.  Press the apply button.
  2. At this stage, you probably have a set of default colors showing in the legend editor.  Here is where ColorRamp comes in.  Press the button.  Create a ramp inside the ColorRamp dialog.  Just mess around at first--the work you do here is harmless--and get used to the simple, flexible choices it offers.  For more information, follow the link to the "screen shot" page.
  3. For a set of quick instructions, resize the ColorRamp dialog by grabbing its right hand side with the mouse and dragging right.
  4. When the your color ramp  looks good, press the Apply button.  The changes will  appear immediately in your view if the theme is visible (the checkmark should be on).  The changes will not appear in the legend editor dialog if it is still open.  The legend editor does not recognize ColorRamp's changes until it has been closed and reopened.
  5. To minimize keystrokes when symbolizing several legends, you may keep the ColorRamp dialog open and select another theme within ArcView or by using the combo box at the top of the dialog.
  6. Keeping the ColorRamp dialog open may consume computing resources.  When you are done with it, dismiss it.  It will always be available at the push of a button from any view in your project.

Tips for More Efficient Use

Your work is automatically saved with the theme

When you applied the color ramp to a  theme, information about the ramp was saved with the theme.  This information will automatically be stored in your ArcView project file.  Whenever you launch ColorRamp with this theme active, it will be loaded with the most recently saved ramp.
Copy a color ramp by changing themes in the dialog

You can copy a color ramp between themes in two ways.  The easiest is to launch ColorRamp from one active theme.  It will start off using that theme's saved color ramp, if any.  Then select another theme in the combo box at the top of the ColorRamp dialog.  If the other theme is in a different view, keep the ColorRamp dialog open while you switch to the other view in ArcView.  Then go back to the open ColorRamp dialog and choose the new theme.  Now press the Apply button.
..or copy a color ramp using Save and Load

The second way to copy a color ramp is to save your ramp as a file.  Simply press the Save button and follow instructions.  Your file will automatically have a ".rmp" extension.  Then launch ColorRamp from another theme--even one in a different project--and use the Load button to reload any saved ramp.  Then press the Apply button.
Undo up to 10 changes with Previous

Do not be afraid to experiment with changing the spectrum in the ColorRamp dialog.  The Previous button will recover up to ten preceding versions.
Save the colors in the existing legend before using ColorRamp

If your theme already has a set of colors you worked hard to create, first save them to a legend file (using ArcView's standard legend editor) before applying a new color ramp.  After you press the ColorRamp Apply button, the color information in the legend will be lost.
Cope easitly with Legend Editor's side-effects

A nasty side-effect of ArcView's legend editor is that it resets all symbols whenever you change the number of classifications, the method of classification, or the classification field.  Don't worry about that!  Remember that your last color ramp is saved with the legend.  After ArcView's legend editor changes the colors, simply re-launch ColorRamp.  It will load with the last ramp saved for your legend: press the Apply button to get your colors back.
Color ramps do not depend on the number of current classifications

Note that the color ramps you create are totally independent of the number of classes in a legend.  This means you can create a ramp when the legend has five classes, say, and then apply it after setting the number of classes to 500.

Technical Notes

These notes respond to questions you may have after using ColorRamp for a while.

The ColorRamp color picker always uses RGB (red, green, blue) values to specify colors, even when you are ramping in HSV or LAB coordinates.  The reason is that these are the values used internally within Avenue to specify colors.  Using any other system would require color coordinate transformations that lose color detail.  (The internal ColorRamp algorithms avoid loss of detail by converting RGB into other systems using floating point arithmetic, rather than integer arithmetic, until the point where actual colors must be communicated to a legend.  Only then are the RGB values rounded.  This maintains the highest possible color fidelity in your maps.)

The "ladder" in the ColorRamp dialog shows the current legend classes relative to your color ramp.  The color assigned to any class will be the one right in the middle of the corresponding box.  Thus, the ladder starts at the middle of the first class and ends at the middle of the last class.  When there are more than 32 classes, however, the ladder would clutter the dialog.  In this case exactly 32 evenly spaced boxes are shown simply to help you divide the full spectrum into even parts; the boxes are no longer related to the existing classes.

Internally, a color ramp consists of exactly the information you supply in the ColorRamp dialog: the positions and colors of the nodes (on a scale of 0 to 256), the colors at those nodes, and the color space to use for interpolation.  This means that the data occupy very little space when saved in your project file.  This is evidenced by the small sizes of any ColorRamp .rmp files you create.  Therefore you should have no concern about creating ramps for legends with many classifications.  This can be useful for displaying grid themes.

However, ArcView itself stores its own legend data in a very cumbersome form.  You will see your project files grow very large very quickly if you start creating lots of legends with hundreds of classes.  Be judicious.

The color ramp information is saved with a theme as an Avenue object tag.  A theme can have only one object tag.  If you are using a script or extension that creates its own object tags for themes, then ColorRamp will refuse to interfere with it.  As a result, the ability to save color ramps with themes automatically may be lost, but you will not lose any data thereby.

Not every legend can have its colors ramped.  ColorRamp will not modify chart legends or image legends (although that may change in the future).

On a slower machine (200 MHz or so) there may be a noticeable delay of a second or two to redraw the ColorRamp dialog.  This is because the spectrum really is a list of 256 distinct color patches and ArcView takes a while to display this list.  The dialog code is optimized to limit the amount of redrawing, but a lot of it is out of our control (such as the redraws that occur while you drag the dialog around).

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Last modified: Thursday October 05, 2000.