Experiment

2.1 Introduction and Hypothesis

There are many different color selection methods that can be used to generate the same exact color. This experiment focuses on comparing the speed and accuracy of four individual color pickers (Crayon, HSV, RGB, CMYK) when asked to match a target color.

We predict that as the dimension of the color picker increases, so will the selection time in which the Crayon will be the fastest, followed by the HSV, RGB, and CMYK pickers. However, the Crayon will be most accurate color picker, followed by HSV, RGB, and CMYK.

Variables:

The independent variable is the color selection method with treatments of 4 different color pickers (Crayon, HSV, CMYK, and RGB).

The dependent variables are time (ticks = 1/60 second) to a select target color, color accuracy (distance of RGB values), and subjective preference (questionnaire).

2.2 Pilot Study Results

Three subjects participated in the pilot study. As a result of the pilot study the following changes were made to the experiment:

• Added a practice session to the beginning of the experiment to introduce the user to each one of the color pickers.
• Some changes were made to the post questionnaire, which involved adding questions and adjusting existing questions, appropriately.
• Increased the amount of trials for each picker from 4 to 8 colors.
• Switched from using all different colors for each trial to using the same set of 8 different colors to be tested on the 4 color pickers.
• Normalized trial colors to Crayon picker color domain to make test colors achievable.
• Added a beep (sound) to notify the subject that they must change the color picker to the next picker to be tested.

Twenty-four undergraduate students from the University of Maryland participated in the experiment.

2.4 Materials

The following materials were used to conduct the experiment:

Hardware:

• A Power Macintosh PC
• 17" monitor with resolution of 1024x768
• Single button Apple mouse

• Apple Color Picker 2.1
• Mac OS 8.5 (operating system)
• Minitab ver. 12.0
• Real Basic 1.0 Mac
• Microsoft Excel

• A subjective questionnaire.

All subjects were seated at a Power Mac workstation. Subjects answered a pre-experiment survey and were introduced to the experiment through a training session. The training session involved explaining the functionality of each of the four color pickers to generate different colors.

This experiment used a within subjects design in which the subject had to match eight pairs of colors for each of the four different color pickers. The color pickers were rotated so that each of the subjects tested would begin with one of the four color pickers. This process started by having the subjects attempt to match the set of eight different target colors, thus producing a beep, which indicated to the subject to switch to the next selection method instructed.

After the subject had gone through each color picker, they filled out a post-survey questionnaire. The questionnaire involved rating each color picker on its accuracy, speed and ease of use on a scale of 1 to 5. This completed the experiment for each subject that was tested, in which they were thanked for their participation.

The following problems were experienced while conducting the experiment:

• A within subjects design was used which creates a learning effect that allows the user to make more accurate matches toward the end of the experiment.
• The user had to manually switch the color picker, which caused the first trial of that picker to take the longest amount of time.
• The screen quality of some of the monitors in the WAM lab which may have slowed the user down in the process of matching certain colors.
• Also, the mouse pads and mouses in the WAM lab may have had an effect on the quality of control for the user, thus forcing user to use test fewer subjects at one time.

Department of Computer Sciences Direct questions and comments to the student editorial team