تويت
الخطوة 1: كيفية عمل الأفلام الملونة .. معالجة الألوان والطباعة .. المرشد خطوة بخطوة للتصوير الفوتوغرافي
STEP 1 : HOW COLOR FILMS WORK
All types of color film ( and most printing papers ) use the same basic principle . They have three layers of light - sensitive silver halides and linked dyes which record and reproduce the subject as three separate color images . Each layer responds to one of the three primary colored wavebands ( blue , green , and red ) that compose white light . As both film and paper use the subtractive principle the subject colors are finally re- produced in the three complementary colors yellow , magenta , and cyan .
Exposure and processing
In the film the top layer responds to blue light . The middle layer responds to green .
And the bottom layer responds to red . All layers respond to white and none of the layers respond to black .
When the film is exposed each layer forms a latent image wherever its primary color was present in the subject . But it is the remaining , unexposed area on each layer , carrying no image , that is important In slide film the dyes in each layer form complementary colored images in these areas . Consequently on the first layer those areas of the image that were not blue carry a yellow dye ; areas that were not green on the second layer carry a magenta dye ; and areas of the image that were not red on the bottom layer carry a cyan dye .
When the slide is viewed in normal white light the three layers recreate the original subject colors by subtracting color from white light . Each dye subtracts one color where that color was not present in the image , and passes the other two .
You can see how the image is formed by following the slide sequence shown below . Slide film is given reversal processing which forms a positive image in the film .
Color negative film is processed to a half- way state in which the tones in the image are negative and the colors complementary . When the negative is enlarged on to color paper it creates the same final dye positives as slide film , as shown below .
The subject
White light is selectively reflected by the subject and gives rise to different colors . These are ana lyzed and separated into combin- ations of the three primary colors by triple emulsion color film .
Latent response
On exposure , three latent images are formed in the layers corres ponding to the color sensitivity of each layer . White produces a res- ponse throughout since it contains all three primary colors . Notice how yellow affects both the red and green sensitive layers .
Dye positives
In the final print or slide each emulsion layer carries a comple- mentary colored image : yellow in the blue sensitive layer , magenta in the green sensitive layer , and cyan in the layer sensitive to red . To- gether these can give any color or tone variation . ( For clarity solid- color is shown here , in practice each image has gradations of dye . )
Overall result
The three layers are permanently superimposed and viewed as one . If the result is a color slide you hold it up to white light , or pro- ject it . On a color print the dye images are seen against white paper . Either way each dye layer removes unwanted light of one primary color . ( Where the three dyes overlap , all three primaries are subtracted and the image appears black . )
STEP 1 : HOW COLOR FILMS WORK
All types of color film ( and most printing papers ) use the same basic principle . They have three layers of light - sensitive silver halides and linked dyes which record and reproduce the subject as three separate color images . Each layer responds to one of the three primary colored wavebands ( blue , green , and red ) that compose white light . As both film and paper use the subtractive principle the subject colors are finally re- produced in the three complementary colors yellow , magenta , and cyan .
Exposure and processing
In the film the top layer responds to blue light . The middle layer responds to green .
And the bottom layer responds to red . All layers respond to white and none of the layers respond to black .
When the film is exposed each layer forms a latent image wherever its primary color was present in the subject . But it is the remaining , unexposed area on each layer , carrying no image , that is important In slide film the dyes in each layer form complementary colored images in these areas . Consequently on the first layer those areas of the image that were not blue carry a yellow dye ; areas that were not green on the second layer carry a magenta dye ; and areas of the image that were not red on the bottom layer carry a cyan dye .
When the slide is viewed in normal white light the three layers recreate the original subject colors by subtracting color from white light . Each dye subtracts one color where that color was not present in the image , and passes the other two .
You can see how the image is formed by following the slide sequence shown below . Slide film is given reversal processing which forms a positive image in the film .
Color negative film is processed to a half- way state in which the tones in the image are negative and the colors complementary . When the negative is enlarged on to color paper it creates the same final dye positives as slide film , as shown below .
The subject
White light is selectively reflected by the subject and gives rise to different colors . These are ana lyzed and separated into combin- ations of the three primary colors by triple emulsion color film .
Latent response
On exposure , three latent images are formed in the layers corres ponding to the color sensitivity of each layer . White produces a res- ponse throughout since it contains all three primary colors . Notice how yellow affects both the red and green sensitive layers .
Dye positives
In the final print or slide each emulsion layer carries a comple- mentary colored image : yellow in the blue sensitive layer , magenta in the green sensitive layer , and cyan in the layer sensitive to red . To- gether these can give any color or tone variation . ( For clarity solid- color is shown here , in practice each image has gradations of dye . )
Overall result
The three layers are permanently superimposed and viewed as one . If the result is a color slide you hold it up to white light , or pro- ject it . On a color print the dye images are seen against white paper . Either way each dye layer removes unwanted light of one primary color . ( Where the three dyes overlap , all three primaries are subtracted and the image appears black . )
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