Hola, una de las maneras posibles, aunque esta en ingles
http://www.pauck.de/marco/photo/lith/digital_lith/digital_lith.htmlO tambien podrias probando lo siguiente
1. Save a copy of the image to the side
2. Alter the original image curve to jack up the contrast and whack the mid and high tones.
3. Alter the copy's curve to lower the constrast and whack the low tones.
4. Mess with the original to increase "grain" -- I skip this since I don't like the graininess.
5. Tone the copy whatever color your want.
6. Merge the two images together in multiply mode.
This technique works great if you like the grain, but if you're primarily aiming at the tonal qualities of lith without regard for the grain (deep sharp black low tones and soft dreamy high-tones), the curves method isn't as satisfactory (even if you skip #4). So far as I can tell, the reason boils down to this: when you use the curves adjustment to increase the contrast and blow out anything that isn't a dark tone, since the curves settings are continuous you necessarily magnify the dark tones, or, to say it differently, you increase the contrast within the dark tones, spacing them out. So two dots that would both be right around zone II may end up in zones II and III -- this separation of what would look just the same helps to produce the grain effect that so many people find pleasing. Using the curves setting you can't really get around this so long as photoshop's curves adjustments are continuous.
But you can get around it if you work with duotones. With duotones, intead of specifying the lightness of a pixel based on its input value, you're specifying the darkness of a pixel -- you're specifying the amount of ink that goes into that slot. The high end of a curves adjustment is brightness (LACK of ink), while the high end of a duotone gradient is darkness (how much ink). By working in the subtractive space of the duotone gradients, you can make a gradient that starts out normal but drops off more quickly than it should with lighter tones. It doesn't keep up with the lighter tones, but as it fails to do so it doesn't "promote" any values into lighter zones -- it squelches the dark tones before they become mid-tones and doesn't create any artificial grain. So to create a duo-tone lith-like print without the grain, you'd follow steps like these:
1. Go to duotones mode (via greyscale if you're not already there)
2. Select both total black and a coloring tone.
3. For the total black gradient, leave the right-hand point all the way at the top, but make the left-hand side flattened all the way to zero until you're about 80% of the way to the right (at which point it shoots up fast to make up the difference). You've just limited the black ink to zones III and lower. If you like, you can make the right hand side flat at 100%, reducing the contrast within the dark zones.
4. For the colored tone, leave the left-most point on the gradient at zero (which is pure white) and lower the right-hand point down to about 50%(or less, according to taste). You've just created a smooth tonal gradient compressed between zones V and X.
When both "inks" are printed on top of each other, then you get a lith-like effect without the grain.
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Tema: Efecto Lith (Leído 2867 veces)
