Friday, March 03, 2006

Color Perception

By : Lukman Nul Hakim

I. PROBLEM

How is the color perception of the subject when color mixing stimulus is presented ?

II. INTRODUCTION

Woodworth and Schlosberg (1971) said that any individual who uses his eyes to see the environment, the retinal image ought to reveal the objects out in front of him in their proper qualities and relations. Carefully considered, however, the retinal image is seriously defective as a direct representation of the environment. There are no objects in the image, but only juxtaposed patches of color. The image, like any other picture, is in two dimensions, the environment in three. The image of an object changes in size and shape as the observer views it from different distances and angles, while the object itself is unchanging. In color too the image changes with the illumination, while the object retains its own color.

EARLY THEORIES
Interest in the problem dates from those early giants of physiological optics, Helmholts and Hering. Intellectual judgement based on unconscious sensations seemed to Hering (1874, 1876, 1879, in Woodworth 1971) an unrealistic account of the process of color perception. He believed that physiological should have more to say on the matter. He pointed to the peripheral factors that compensate for changes of illumination; contraction and dilation of the pupil, retinal adaptation and contrast. He admitted that these peripheral factors we not wholly sufficient and accordingly suggested also a cerebral factor. The sensory affect of any stimulus, he said, depends not only on the retina but also on the receiving center of the brain, the sensorium, and the brain structure may be modified by use in loking at objects. With a modified sensorium we get a modified sensation from the same stimulus, and our impression is thus an actual sensation and not an intellectual judgement.
This approximate color constancy of seen object, hering urged, was one of the most remarkable and important facts in the whole realm of physiological optic.

WHAT ARE OBJECT COLORS?
An important distinction between surface color and other color was made by Katz (1911, 1930), who was trying to discover how the color patches of the retinal image appear to the naïve observer. Most of the patches appear to be surfaces of objects, and their color appears to be present in these surfaces.

THEORIEST OF COLOR VISION
Young proposed the three component theory which then developed by Helmholtz (1856-1866), and today become dominant. The four component theory was proposed by Hering (1874), and an interesting combination of both theories was devised by Ladd Franklin (1929).

COLOR MIXING
The dependence of hue on wavelength, as already stated, is very definite. Aside from certain effects of intensity and of peripheral vision, each wavelength gives a specific hue. But the converse of this proposition is not true. Each hue is not bound to a specific wavelength. The same yellow hue which we get from a homogenous ray of wavelength 580 mm can be obtained from a mixture of 570 and 590, and from an indefinite number of mixtures centering about 580. any hue can be obtained from suitably balanced mixtures of wavelengths, and in fact most of the colors we see are produced by mixed lights, since homogenous rays seldom reach the eye.
The sensation obtained from a mixed light is apt to be less saturated than from a homogenous light, but as far as hue is concerned the effect is unitary in both sexes. The effect is altogether difference from that obtained in the auditory sphere by mixing two wavelengths (or frequencies). Color mixture is not a mixture of sensation, but a mixture of stimuli which gives a unitary sensations. Yellow, though surely a unitary hue, can be obtained by mixing red and green lights, and white can be obtained by mixing yellow and blue.

RESULT IN COLOR MIXING
By mixing red and yellow in different proportions we obtain all the orange hues intermediate between our red and yellow. By mixing red and grass green we get all the hues of orange, yellow and yellowish green. It might seem that we had found a rule, to the effect that mixing any two colors of the spectrum gave the intermediate colors. But when we push the matter a little further by mixing red and a bluish green, we get no intermediate hues. If red predominates in this particular mixture we get only unsaturated shades of red; if the bluish green dominates we get unsaturated shades that same green; and if the red and the bluish green are rightly balanced we get white or gray. Red and this particular bluish green are said to be complementary. If we advanced still further and mix red and blue, in different proportions, we obtain all the hues of purple and violet. In the spectrum, these hues are not intermediate between red and blue, but in the color circle they are intermediate around the back way.

III. METHODS

HYPOTHESIS
Hypothesis One
When two primary colors which is complementary are mixed together in particular proportion, then it will produce the third color, which is gray.
Hypothesis Two
When two primary color which is not complementary are mixed together, then it will produce a shade of both color.

VARIABLES
Independent Variable : Color mixing
Dependent Variable : Color perception

MATERIAL REQUIRED
q Discs or some colors
q Apparatus to mix color
q Paper
q Pencil

PRELIMINARIES
Name : Heni Kent
Age : 23 years old
Sex : Male
Place : Psychology Laboratory of Jamia Millia Islamia



STEP BY STEP PROCEDURE
q Prepare the color mixing apparatus
q Prepare the color discs
q Prepare the seating position
q Presenting the stimulus to the subject
q Ask the subject to give responses

RAPPORT FORMATION
A brief conversation was held with subject to make subject feel comfortable with the experimental situation.

INSTRUCTION
‘Dear friend, I will show you some color disc one to another, and you just need to tell me the color that you see’.

CONDUCTION
First we decide which color will be the main color and which one that we going to gradually change. Then the subject was presented with the color mix stimulus, session by session, in which on every session after subject has given the answer about the stimulus, then the experimenter change the percentage proportion of the disc combination. In total there are 2 pair of color combination.

INTROSPECTIVE REPORT
This experiment is an interesting one, I learn a lot of new things today by participating this experiment.

IV. RESULT

TWO PRIMARY COLOR WHICH COMPLEMENTARY MIX TOGETHER
Combination between red and green
Degree
1
2
3
4
5
6
7
8
9
10
A
D
A
D
A
D
A
D
A
D
340-20
red
Green
red
Green
red
Green
red
Green
red
Green
320-40
red
dark green
red
dark green
red
dark green
red
dark green
red
dark green
300-60
maroon
dark green
maroon
dark green
maroon
dark green
maroon
dark green
maroon
dark green
280-80
maroon
Gray
maroon
darker green
maroon
Gray
maroon
Gray
maroon
Gray
260-100
maroon

maroon
Gray
maroon

maroon

maroon

240-120
maroon

maroon

maroon

maroon

maroon

220-140
brown

brown

brown

brown

brown

200-160
brown

brown

brown

brown

brown

180-180
brown

brown

brown

brown

brown

160-200
brown

brown

brown

brown

brown

140-220
Gray

gray

Gray

gray

gray


Combination between blue and yellow
Degree
1
2
3
4
5
6
7
8
9
10
A
D
A
D
A
D
A
D
A
D
340-20
Blue
yellow
blue
yellow
blue
yellow
blue
yellow
blue
yellow
320-40
Blue
yellow
blue
yellow
blue
yellow
blue
yellow
blue
yellow
300-60
gray
yellow
gray
yellow
gray
yellow
Gray
yellow
gray
yellow
280-80

yellow

yellow

yellow

yellow

yellow
260-100

yellow

yellow

yellow

yellow

yellow
240-120

yellow

yellow

yellow

yellow

yellow
220-140

yellow

yellow

yellow

yellow

yellow
200-160

gray

gray

gray

gray

gray
180-180










160-200










140-220











TWO PRIMARY COLOR WHICH NON COMPLEMENTARY MIX TOGETHER
Combination between red and yellow
Degree
1
2
3
4
5
6
7
8
9
10
A
D
A
D
A
D
A
D
A
D
340-20
Red
Yellow
Red
Yellow
Red
Yellow
Red
Yellow
Red
Yellow
320-40
Red
Yellow
Red
Yellow
Red
Yellow
Red
Yellow
Red
Yellow
300-60
Red
Orange
Red
Orange
Red
Orange
Red
Orange
Red
Orange
280-80
Red

Red

Red

Red

Red

260-100
Red

Red

Red

Red

Red

240-120
Orange

Orange

Orange

Orange

Orange

220-140










200-160










180-180










160-200










140-220











Combination between blue and green
Degree
1
2
3
4
5
6
7
8
9
10
A
D
A
D
A
D
A
D
A
D
340-20
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
320-40
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
300-60
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
280-80
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
260-100
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
240-120
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
220-140
Blue
Green
Blue
Green
Blue
Green
Blue
Green
Blue
Green
200-160
Blue
Light green
Blue
Light green
Blue
Light green
Blue
Light green
Blue
Light green
180-180
Light green
Blue
Light green
Blue
Light green
Blue
Light green
Blue
Light green
Blue
160-200
Light green

Light green

Light green

Light green

Light green

140-220
Green

green

green

green

green



CONCLUSION
The first hypothesis says that when two primary colors which is complementary are mixed together in particular proportion, then it will produce the third color, which is gray. And the result of the experiment support the hypothesis. On red-green combination when the degree of the red is 140 and the green is 220 the result color is gray, and when the degree is decreased for the red and the opposite for the yellow up to 80-280 the result color is still gray. On 60 (red) – 300 (green) combination then the color start to be dark green. This finding support the hypothesis.
On blue – yellow combination when the degree of the blue is 300 and the yellow is 60 the result color is gray. And by descending combination (yellow-blue) the color start to become gray on 160– 200 degree combination. This finding also support the first hypothesis.
The experiment also support the second hypothesis, which stated that when two primary color which is not complementary are mixed together, then it will produce a shade of both color. In red-yellow combination the result varied from red to orange, and by blue-green combination it creates blue-light green and then green.
The result of the experiment support both hypothesis.
V. DISCUSSION

As mentioned by Woodworth (1971), he has found the rule of color mixing. To the effect that mixing any two colors of the spectrum gave the intermediate colors. But when we push the matter a little further by mixing red and a bluish green, we get on intermediate hues. And if we experimenting with other pairs of colors we obtaine similar result. When two colors differ comparatively little in wavelength, their mixture gives the intermediate hues, when they differ just enough they are complementary, and when they differ by more than this amount they give the purples. The color that two components will give always lies on a line connecting the two components in the color spindle. Its precise position on the line will be determined by the relative proportions of the components. Thus the color spindle summarizes the facts of color mixture in a convenient way.

1 Comments:

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7:30 PM  

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