ColorMap can help colour blind users in reading maps, seating plans and other content where colour is used to convey information.

Geography teachers can use ColorMap to make Choropleth maps accessible to colour blind students.

ColorMap is available in two versions:


Hover over the legend to see the map change. Alternatively, move focus to the map and then use the Arrow keys.

Map of Australia showing total forecast rainfall between 30 March and 06 April 2013. The map is divided into areas with different colours. A legend indicates which amount of rain each colour represents e.g. green is between 25 and 50mm. Copyright Commomwealth of Australia 2013. Australian Bureau of Meteorology. Issued 29 March 2013

ColourMap - online tool

Step 1 of 2: Paste or drag an image to the box. Alternatively, upload a file.


How to use online tool

Once you've dragged an image file to the box above, click on each of the colours in the legend, then hover the mouse over a legend item to see the corresponding colour turn black on the map. Alternatively, move focus to the map then use the Arrow keys to select a legend item.

Clicking on a legend item (or pressing the Enter key when it has focus) will freeze the map in this view so you can move the mouse without changing the view. This can help screen magnifier users as they use the mouse to navigate the screen. It also comes in handy for keyboard users as they can use the Arrow keys to scroll the page when the map is frozen.

Hovering over a legend and pressing the delete key removes the legend.

Key Function
Arrow Move between legends
Enter Freeze current legend
Delete Remove current legend
Escape Unselect current legend
B Toggle black and white mode

Locking the map

Clicking the lock button removes the ability to create new legends, so you can click around on the map as you wish.

Changing tolerance

The drop-down box can be used to change the colour tolerance. If the legend colour is different from the colour on the map it might be necessary to use a greater tolerance e.g. change the drop-down from 20 to 50 and then clicking to create a new legend.

Reading colours

Clicking the diamond icon shows a hue-saturation- lightness graph in the top left corner of the screen. The graph shows the colour of the pixel that is hovered over with the mouse.

Keyboard mode

Clicking the keyboard icon displays a yellow circle in center of the map. The circle can be moved using the keyboard Arrow keys and pressing Enter created a legend item on the map. This enables keyboard users to create legend items.

Key Function
Arrow Move yellow circle one tenth of the map
Alt + Arrow Move yellow circle 1 pixel
Shift + Arrow Scroll webpage
Enter Create a legend under yellow circle
C Place yellow circle in the centre of the map and reset bisecting navigation
Ctrl + Arrow Move yellow circle in bisecting distances: for each move the distance is halved
Escape Exit keyboard mode

Black and white mode

This mode shows all legend pixels as black and all other pixels as white.

Tip: use the Down and Up arrow keys to cycle through legends and use the B key to toggle between standard view and black and white view.

Show legends

The Show legends function creates a web page with images of the legends. This can be printed if a hardcopy is needed (you can print as PDF from browser). The content cannot be copied and pasted.

It can take a while to generate the print version. For large image files you might have to do one legend at the time and then combine the PDF documents.

Map of Australia showing total forecast rainfall between 30 March and 06 April 2013. On this map, the green colour is replaced with a black grid on a white background. This has been done on both the map and in the legend. A second map shows the green colour replaced with a black fill and all other content removed.

Download legends

This function works like "Show legends" except it downloads the web page to your Downloads folder. And, it doesn't work in IE.

The content can be copied and pasted e.g. into Word for editing.

If your browser shows a dialog box with "Open" and "Save" options, choose "Save".

ColourMap - webmaster script

The colourmap functionality can be added to any image by including a call to the colourmap function. On pageload, the image is swapped with a canvas element with built-in colourmap functions. This is shown in the demo at the top of the page.

Note: the webmaster version does not allow users to create or delete legend items.

You can get the ColourMap webmaster script from our Downloads page.

Code for making an image a colourmap:

<script type="text/javascript">
    visionaustralia.addcolourmap ("rainmap",40,[[490,70],[490,90],[490,110],[490,135],[490,155],[490,170], [490,195],[490,225],[490,240],[490,260],[490,285],[490,300]]);

The arguments to the addcolourmap function are:

  1. id of the image
  2. Number between 0 and 100. 0 means that only the exact pixel colour will be recognised, higher numbers allow for variation in the colour.
  3. Array of points. Each point represents a pixel within a legend colour. You can get these numbers by opening the image in Microsoft Paint and hover the mouse over a legend area, the x and y-values are displayed in lower left section of the window. Any point within the coloured legend area will usually do.

Terms of Use

Developed by Pierre Frederiksen. Pierre is a Principal Technical Consultant at Vision Australia

This software is being provided "as is", without any express or implied warranty. In particular, Vision Australia does not make any representation or warranty of any kind concerning the reliability, quality, or merchantability of this software or its fitness for any particular purpose. additionally, Vision Australia does not guarantee that use of this software will ensure the accessibility of your web content or that your web content will comply with any specific web accessibility standard.

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This work is licensed under a Creative Commons License