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Ink to Light Conversion Chart  - or

Photoshop Eight Bit Luminosity to Percent of Gray Conversion Reference

category: graphics, digital photography and image editing

Grayscale images, or RGB images by channel, are described and manipulated in Photoshop by luminosity values ranging from 0-255. When viewed on screen, black is no light or 0, and white is maximum light or 255. When printed, an image is described in terms of ink needed to produce a given result on paper. No ink or 0% is white, and maximum ink or 100% is black, just the reverse. Sometimes you need to know that 50% gray is 128, or 3% gray is 248. Photoshop runs on a computer and can make these kinds of conversions quickly; you and I could use a chart. The Conversion Reference can be found in the continued portion of this entry.

100%.......0..........66%......87..........32%.......174
.99%.......3..........65%......90..........31%.......177
.98%.......5..........64%......92..........30%.......179
.97%.......8..........63%......95..........29%.......182
.96%......10..........62%......97..........28%.......184
.95%......13..........61%.....100..........27%.......187
.94%......15..........60%.....102..........26%.......189
.93%......18..........59%.....105..........25%.......192
.92%......20..........58%.....108..........24%.......195
.91%......23..........57%.....110..........23%.......197
.90%......26..........56%.....113..........22%.......200
.89%......28..........55%.....115..........21%.......202
.88%......31..........54%.....118..........20%.......205
.87%......33..........53%.....120..........19%.......207
.86%......36..........52%.....123..........18%.......210
.85%......38..........51%.....125..........17%.......212
.84%......41..........50%.....128..........16%.......215
.83%......44..........49%.....131..........15%.......218
.82%......46..........48%.....133..........14%.......220
.81%......49..........47%.....136..........13%.......223
.80%......51..........46%.....138..........12%.......225
.79%......54..........45%.....141..........11%.......228
.78%......56..........44%.....143..........10%.......230
.77%......59..........43%.....146...........9%.......233
.76%......61..........42%.....148...........8%.......236
.75%......64..........41%.....151...........7%.......238
.74%......67..........40%.....154...........6%.......241
.73%......69..........39%.....156...........5%.......243
.72%......72..........38%.....159...........4%.......246
.71%......74..........37%.....161...........3%.......248
.70%......77..........36%.....164...........2%.......251
.69%......79..........35%.....166...........1%.......253
.68%......82..........34%.....169...........0%.......255
.67%......84..........33%.....172

He said on 08.02.05 @ 12:51 PM CST