>> Dear Thomas, I have great curiosity about this info. Is this just so simple? If so, what is the use or rationale to include all other color patches in the card ( 24 in total)? I find that if I set ( in Levels) the White point first ( at a value of , say 245 instead of 255) and followed by the Black POint ( set at 10 or 15) then there is no way I can have the Grey point to fall in the Expected 128 target value. <<
Jorge, on the four middle gray patches between white/black, the L of LAB idealised reading is close to (light to dark, left to right): 81L, 66L, 50L, 35L or in A98 200rgb, 159rgb, 119rgb, 83rgb (quickly measured of my digital colourchecker action based on published measurements). It would be more critical to get the neutral patches neutral (zero AB LAB readings or R=G=B) - I would not worry about the brightness too much. In a linear space the 128 value would be midway, but it is my guess that most do not use gamma1 edit spaces. Stephen Marsh. =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
