Here's an exercise for describing images from one sense in terms of others.
http://www.unco.edu/poetry/jeffrey.lee/ ... thesia.htm
The following text is quoted from the above site. Text by Jeffrey Ethan Lee, PhD, MFA.
Synesthesia Writing Exercise
Painters traditionally spend a great deal of time working with a palette of colors before they start painting. This is an important step in the process because the artist begins making decisions about the work in the process of creating the colors that will be used. Poets and writers have not traditionally spent time developing a “palette” of language before they start writing, but this is actually a great way to get started with writing or revising a work. The idea of this synesthesia exercise, below, is to help poets and writers create new “colors,” and these new “colors” can help them to realize other ways to see and hear and represent whatever their themes may be.
Start with an auditory phenomenon such as a piece of music, an environmental sound, or even a particular auditory environment such as a certain interior (or exterior) building space. Listen to the sound or sound environment while you are writing. Describe the auditory phenomenon as accurately as you can without using any auditory or sound-related words. That is, you must think about sound as though it were full of colors, temperatures, textures, scents, flavors, and even kinesthetic sensations. For example, one poet wrote a piece that transfigured sounds into the way one would dance to them; she “choreographed” the sound and made herself the “dancer.” Try to invent at least ten good lines for whatever you are describing.
Start with a visual art work or any available visual phenomenon, and really look at it in terms of its components, its textures, its light-dark values, etc. Always keep the thing in front of you and/or in the forefront of your consciousness. Then describe the thing as accurately as you can but without using any visual words. You have to transfigure your visual ideas into sound, smell, touch, taste, and kinesthesia ideas. Try to invent at least ten good lines for whatever you are describing.
Look over your best lines from both of the above and combine them into one poem about one thing (or a few related things).
(Suggestion: if you don't know what to write about, read over your synesthesia-inspired lines and see what they suggest to you. Try not to resist whatever direction the language takes you. It probably will want you to go in a certain direction, and there is probably a reason for that...)
Public Dreaming Variation
Someone said that the artist is like a public dreamer, i.e., the artist is one who dreams for the sake of the public. In this variation of the synesthesia exercise, first decide upon a dream that is vivid and meaningful to you. It could be one of your own dreams, the dream of someone you know, or even a famous dream that you read about in a psychology book or a work of art.
Second, write down the essential parts of the dream (the main images, the main “plot” if there is one, the primary sounds, colors, tastes, and any other sensory information). You can refer back to this as though it were an outline for what follows.
Third, take the most important visual elements of the dream and transfigure them into any or all of the other senses.
Fourth, you may repeat this process for all the auditory elements, and transfigure then into any or all of the other senses.
Fifth, you may repeat this process for any other important elements of the dream.
Sixth, remember that you can always go back later and add back in the essential visual and auditory elements if you need them!
Seventh, and finally, copy out the entire dream by hand from start to end at least three times and revise it until it makes a complete or “finished” draft.
Advisory: this exercise is HARD! And it will probably take you places that are strange and different for you even if you are an experienced writer. On the other hand, it may open up new avenues for you that are extraordinary and powerful, luminous in ways you have never dreamed you could imagine.