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GELFILE | Specifications | Instructions | Applications | Color Theory | Purchase | Help


GelFile is a program which allows you to examine the characteristics of over 1300 different plastic and glass color filters which are manufactured for the entertainment industry.

  • Using the Chromaticity Plot, the Brightness Graph and various lists, GelFile will provide technical and descriptive information for any or all of the gels.

    The manufacturer's number and name are still the main description, so you don't need to learn a new system.

    Each gel can be found on both the Chromaticity Plot and the Brightness Graph.

    Each gel is described in terms of its color (Dominant Wavelength) and the saturation (Purity).

    The Brightness, which is very much like transmission, of each gel is shown.

  • With the "MODE" and "INVENTORY" functions you can select whether you want to work with the whole catalog of gels, or just with a select group.
  • Using the function called "DUMP", you can learn quickly which parts of the Chromaticity Plot a given brand of gels covers. You can even see what range all of the gels cover.
  • Using the "MIX" function, you can get a list of all colors which three gels will mix. You can also define an area on the screen, and GelFile will help you select the three colors which you can use to achieve that range on stage or on a drop. This function also allows you to examine the relationship between any two gels.
  • With the "MATCH" function, you can discover which gels are similar to some particular "target" color. This function allows you to adjust the range of search.
  • You can print out lists of colors related to any of the above functions.


Some definitions will be helpful. These are the most commonly used terms in this manual and on the screen:


It seems obvious, but this is what we call a particular color filter found in a manufacturer's brand.



A manufacturer's collection of gels, usually bound in a sample ("swatch") book. Some manufacturers (well, just one, really) have many different collections of gels in different swatch books. Each of those collections is called a "brand". GamColor is one brand for example.



This is what we call a gel or gels you have selected for the MATCH or MIX function. For example, if you ask GelFile what colors match GAM 110, GAM 110 is the target, and the colors GelFile lists are the "matches".



The list of all gels in all brands is called the Catalog. It comes preloaded with the program and cannot be altered.



A list of gels you have selected and put into a separate list for ease of management. The most obvious use of the list is to limit your searching to those gels you have available at your theater, but there are other ways you can use it, as you will discover later.



There are two modes in GelFile: CATALOG and INVENTORY. You choose to work with either the complete list of gels or with your own select list by clicking on the MODE button.


GelFile is descended from the book Color Science for Lighting the Stage which two of the authors wrote in 1981. The purpose then, as now, was to help people organize their thinking about color filters according to a standard system which was widely used and able to be checked against internationally accepted standards. The system selected was CIE 1931 colorimetry, which is described in the following section.

The authors planned to republish the book from time to time with up-to-date information, but the unwieldy nature of the test equipment available then, and the long lead time required to publish a new book made that impractical. Also, the cost of color printing prevented the book from being as descriptive as might have been hoped. The arrival of the personal computer and improved testing hardware have now made it possible to convert the book to GelFile.

The time in Los Angeles, California is 05:13 am Saturday, September 26, 2020.
The GAM staff is on duty to answer your questions from 8:00 a.m. to 5:00 p.m., Monday through Friday (except holidays).
For assistance, call toll free in the US and Canada 888-GAMCOLOR or 323-935-4975 (Country code 1).

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