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lines in a brick-like fashion. In a perfect world, this would cover exactly half of the page with ink and make the page appear to have 50% reflectivity. However, because the ink will bleed into its neighboring target locations, greater than 50% of the page will be dark. To compensate for this darkening, a TRC is applied and the digital image's reflectance value is reduced to something less than 50% dot coverage. When digital halftoning is performed, we will no longer have the uniform on-off-on-off pattern, but we will have another pattern that will target less than 50% of the area with ink. If the correct TRC was chosen, the area will have an average 50% reflectance after the ink has bled.
77:, the differences between an "objective" and "subjective" tone reproduction, and between "accurate" and "preferred" tone reproduction, have long been recognized. Many steps in the process of photography are recognized as having their own nonlinear curves, which in combination form the overall tone reproduction curve; the
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As an example, suppose one wants to print an area at 50% reflectance, assuming no ink is 100% reflective and saturated black ink is 0% (which of course they aren't). The 50% could be approximated using digital halftoning by applying a dot of ink at every other dot target area, and staggering the
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of a particular printing method. Dot-based printing methods have a finite native dot size. The dot is not square, nor any other shape that when stacked together perfectly fills an image area; rather, the dot will be larger than its target area and overlap its neighbors to some extent. If it were
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of the film. The gamma can be controlled by choosing different films, or by varying the development time or temperature. Similarly, the light transmitted by the negative exposed a
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and interacts with the characteristic curve of the paper to give an overall tone reproduction curve. The exposure of the paper is sometimes modified in the darkroom by
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tend to be nearly linear, but these nonlinear tone reproduction characteristics are emulated in the camera hardware and/or processing software, via "
132:, further complicating the overall tone reproduction, usually helping to map a wider dynamic range from a negative onto a narrower print
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of the print closely approximates a proportionality to the luminance intent implied by the electronic image.
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was developed as a way to illustrate and combine curves, to study and explain the photographic process.
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of the exposure (also called a D–logE curve) has central straight section whose slope is called the
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responds nonlinearly to the exposure, as characterized by the film's characteristic curve, or
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298:"On the Theory of Tone Reproduction, with a Graphic Method for the Solution of Problems"
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is often referred to by its initials, TRC, and the 'R' is sometimes said to stand for
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is used to reduce the exposure range to less than the scene luminance range. The
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technologies. However, the need also applies to continuous-tone methods such as
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In printing, a tone reproduction curve is applied to a desired output-referred
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Leslie D. Stroebel; Ira
Current; John Compton & Richard D. Zakia (2000).
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smaller than its target area, it would not be possible to saturate the
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308:(1). The Franklin Institute of the State of Pennsylvania: 39–90.
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in a camera, not necessarily directly proportionally, as when a
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conversion. For example, by default, when transforming from
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tones is one of the long-time concerns of photographers.
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John Sturge; Vivian
Walworth & Allan Shepp (1989).
43:, with the aim of subjectively "properly" reproducing
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It is easier to demonstrate the need for a TRC using
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391:Basic Photographic Materials and Processes
355:Journal of the Optical Society of America
88:range of a scene maps to the focal-plane
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332:American Engineer and Railroad Journal
163:value, for example to adjust for the
112:of the developed negative versus the
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50:The reproduction of color scenes in
415:Charles Hains; et al. (2003).
351:"Photographic Reproduction of Tone"
226:and 20% dot gain for coated paper.
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394:. Focal Press. pp. 235–255.
302:Journal of the Franklin Institute
202:A TRC can be applied when doing
98:graduated neutral density filter
272:Imaging Processes and Materials
421:Digital Color Imaging Handbook
47:and "brightness differences".
1:
314:10.1016/S0016-0032(20)92118-X
328:"A New Photographic Process"
65:as in tone response curve.
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419:. In Gaurav Sharma (ed.).
349:L. A. Jones (March 1921).
222:profile for SWOP standard
417:"Digital Color Halftones"
296:L. A. Jones (July 1920).
183:printing methods such as
24:is the mapping of scene
275:. John Wiley and Sons.
59:tone reproduction curve
455:Photographic processes
106:Hurter–Driffield curve
375:10.1364/josa.5.000232
338:(4): 183. April 1894.
367:1921JOSA....5..232J
141:digital photography
193:photographic paper
122:photographic paper
22:tone reproduction
16:In the theory of
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236:Curve (tonality)
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110:optical density
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69:In photography
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246:Jones diagram
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251:Tone mapping
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218:applies an
204:color space
189:xerographic
174:reflectance
155:In printing
134:reflectance
90:illuminance
75:photography
34:reflectance
18:photography
444:Categories
257:References
195:printing.
130:burning-in
45:brightness
216:Photoshop
181:halftoned
170:substrate
161:luminance
114:logarithm
86:luminance
63:response,
41:luminance
32:to print
26:luminance
450:Printing
241:Dot gain
230:See also
165:dot gain
94:exposure
363:Bibcode
136:range.
128:and/or
126:dodging
38:display
427:
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336:XLVIII
279:
208:L*A*B*
185:inkjet
149:curves
187:, or
118:gamma
30:color
425:ISBN
396:ISBN
277:ISBN
224:inks
212:CMYK
102:film
92:and
84:The
28:and
371:doi
310:doi
306:190
220:ICC
210:to
151:".
139:In
73:In
36:or
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359:V
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