Creating curves with 21step & curve template
2005-07-14 by Chris Aitken
Hi all, I have printed off Paul R's 21step from [1], and then using a densitometer here at work, put the figures into the Curve Template spreadsheet [2]. Here are my results: |densities-----------| Photoshop RGB-----| Step measured corrected input output measured nominal 0 0.89 0 255 255 5 0.94 0.05 239 242 10 1.02 0.13 215 230 15 1.11 0.22 190 217 20 1.16 0.27 177 204 25 1.22 0.33 163 191 30 1.27 0.38 151 179 35 1.35 0.46 134 166 40 1.41 0.52 122 153 45 1.47 0.58 111 140 50 1.54 0.65 99 128 55 1.62 0.73 86 115 60 1.68 0.79 77 102 65 1.76 0.87 66 89 70 1.83 0.94 57 77 75 1.92 1.03 46 64 80 2.01 1.12 37 51 85 2.17 1.28 22 38 90 2.36 1.47 7 26 95 2.39 1.5 5 13 100 2.46 1.57 0 0 My value for the paper base is also the same as the zero step - I'm guessing that this is what it should be (as the results look similar to the as-downloaded results. Now where to input these figures into photoshop? The transfer function curve in the print dialog requires percentages - as does the curve tool. I'd really appreciate some guidance here! Cheers Chris [1] http://f2.grp.yahoofs.com/v1/cA3WQssvJtKYYC_rD-ac2sdm-peMBhBOc8AOz3RKssEchbi KTZ25-bvZcLwsehOkgSA9XWalogbaJZp584XO7hGptJQFBl1NEMimXbN3/Image%20Processing /21-Step%2B.jpg [2] http://f1.grp.yahoofs.com/v1/cA3WQtp3fQiYYC_rmFvDtwxzj6vb7npe3DbP4_h4Y9O_m4K b6oIistFtzBTB5vlmIG1iA0rYl_DY1BWj38AAl9-JWil1-3F8lMm3eMT6/Image%20Processing /CurveTemplate.xls -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.