Photographic printing
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- This article focuses on optical/chemical printing. For non-optical digital printing, see Digital printing.
Photographic printing is the process of producing a final image for viewing, usually on sensitized paper from a previously prepared photographic negative or from a positive transparency or slide.
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[edit] Printing from a Negative
The process consists of three major steps, performed in a photographic darkroom or within an automated photo printing machine:
- Exposure of the image onto the sensitized paper using a contact printer or enlarger
- Processing of the latent image through a multistep chemical immersion process.
- Development of the exposed image. This step reduces the silver halide in the latent image to metalic silver.
- Stopping development by neutralizing, diluting or removing developing agent.
- Fixing the final print by dissolving remaining unexposed/undeveloped silver halide from the light-sensitive emulsion.
- Washing thoroughly to remove chemicals used in processing, protecting the finished print from fading and decay.
- If made on glossy paper, ferrotyping to enhance the reflective gloss.
- Optional Toning of the print through additional chemical processes that replace all or part of the reduced silver in the image with other pigments.
- Texturing and drying of the final print.
Optionally after fixation, the paper is treated with a hypo-eliminator to ensure complete removal of the fixative, which would otherwise compromise the long term stability of the image. In processing color prints additional steps are added to form the color pigments from precursors in the different color-sensitive layers of the emulsion.
[edit] Printing from a Slide or Transparency
Printing from a slide or transparency is similar to printing from a negative except that additional processing steps are added to form a reversal print.
Initial development of the print results in a negative image. This development is not followed by fixation, but rather the reduced silver of the negative image is chemically removed from the paper. Since the paper has not been fixed, the unreduced silver halide remains in the emulsion. To form the positive image, the paper is then exposed to light, which creates a latent image in the unreduced silver halide coating. This latent image is developed and fixed to form the positive image.
[edit] Standard print sizes
Standard photographic print sizes are often denoted with a code of the format nR, where the number n represents the length of the shorter edge in inches. In the normal series, the long edge is the length of the short edge plus 2 inches (10" or less) or 3 inches (11" and above). The alternative Super series, denoted SnR has an aspect ratio of 2:3 (or as close as possible) and thus provides a better fit for standard 135 film (35mm) at sizes of 8 inches or above.
In Japan, the same print sizes (and several additional ones) are known by different names. The Japanese L is equivalent to 3R, while 2L — twice the size — matches 5R. KG represents the size of a traditional 4"×6" (4R) Japanese postcard (hagaki).[1] The nP or cut (切り kiri?) series are defined in reference to a full page size (全紙 zenshi?) of 457×560 mm, with smaller numbers (fewer cuts) indicating larger sizes.[2]
Unlike ISO 216 paper sizes, the aspect ratios of photographic prints vary, so exact scaling of prints is not always possible. However, there are some logical correspondences between the sizes, noted below when applicable.
| Japan | Size (in.) | Size (mm) | 300dpi (px) | Aspect ratio | Note | |
|---|---|---|---|---|---|---|
| E | 3¼" × 4½ | 82.5 × 120 mm | 11:16 (0.69) | Size in inches is approximate | ||
| 3R | L | 3½" × 5" | 89 × 127 mm | 1051 x 1500 px | 7:10 (0.70) | Called "9cm x 13cm" worldwide. |
| 4R | KG | 4" × 6" | 102 × 152 mm | 1205 x 1795 px | 2:3 (0.67) | Standard consumer print size in US and Canada. Called "10cm x 15cm" worldwide. |
| 5R | 2L | 5" × 7" | 127 × 178 mm | 1500 x 2102 px | 5:7 (0.71) | Twice the size of a 3R print. Called "13cm x 18cm" worldwide. |
| 6R | 8P | 6" × 8" | 152 × 203 mm | 1795 x 2398 px | 3:4 (0.75) | Twice the size of a 4R print. |
| 8R | 6P | 8" × 10" | 203 × 254 mm | 2398 x 3000 px | 4:5 (0.80) | Most common print size for medium and large format. Called "20cm x 25cm" worldwide. |
| S8R | 6PW | 8" × 12" | 203 × 305 mm | 2398 x 3602 px | 2:3 (0.67) | Closest approximation to A4, twice the size of a 6R print. Called "20cm x 30cm" worldwide. |
| 10R | 4P | 10" × 12" | 254 × 305 mm | 3000 x 3602 px | 5:6 (0.83) | |
| S10R | 4PW[3] | 10" × 15" | 254 × 381 mm | 3000 x 4500 px | 2:3 (0.67) | |
| 11R | 11" × 14" | 279 × 356 mm | 3295 x 4205 px | 11:14 (0.79) | Called "28cm x 36cm" worldwide. | |
| S11R | 11" × 17" | 279 × 432 mm | 3295 x 5102 px | 11:17 (0.65) | ||
| 12R | 12" × 15" | 305 × 381 mm | 3602 x 4500 px | 4:5 (0.80) | ||
| S12R | 12" × 18" | 305 × 465 mm | 3602 x 5492 px | 2:3 (0.67) |
[edit] References
- ^ デジカメプリント料金・サイズ・支払い方法・発送方法 -デジカメプリントのPAM
- ^ Traditional Japanese Specialty Papers
- ^ At 368mm, the Japanese 4PW size is slightly narrower than S10R.
[edit] See also
- List of photographic processes
- Film developing
- Gelatin-silver process
- Enlarger
- Contact print
- Photographic print toning
- Photographic paper
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