I have some images that have ideal color and good black and white points, but need some overall lightening for printing on the new Epson Exhibition Fiber paper.[a href=\"index.php?act=findpost&pid=164880\"][{POST_SNAPBACK}][/a]
Same problem here. With my Epson 3800 printer, most prints come out too dark (on any paper). The tones are all here, no murky shadows ... but still the overall impression is too dark.
The two ways I know of to do this are to use either a curves adjustment layer, and bow the curve upward slightly leaving the endpoints fixed ... or, use a levels adjustment layer and shift the midpoint slightly. I am trying to understand the difference between these two approaches.[a href=\"index.php?act=findpost&pid=164880\"][{POST_SNAPBACK}][/a]
There is none.
If you just do a slight midpoint (gamma) move in Levels, it will look very much like a slight Curve adjustment. But the data is being manipulated differently.[a href=\"index.php?act=findpost&pid=164883\"][{POST_SNAPBACK}][/a]
No, it's not. As long as you're using just
one additional point to manipulate the curve (and leave the endpoints alone), the effect will be exactly the same as moving the middle (gray) slider in Levels. The whole Levels dialog is just a different (simpler) user interface to the Curves functionality.
Curves gives much more control than Levels.[a href=\"index.php?act=findpost&pid=164883\"][{POST_SNAPBACK}][/a]
More control, yes. Still there is nothing in Levels that you can't do in Curves also. In Curves, you can do anything that you can do in Levels, and then some.
Does this mean the Levels dialog is obsolete? No, it doesn't, because some kinds of manipulation are easier and/or quicker to do via Levels than through the more complex---and thus, more powerful---Curves interface.
And whenever possible make sure you're doing your editing in 16-bit.[a href=\"index.php?act=findpost&pid=164883\"][{POST_SNAPBACK}][/a]
That's good advice---but it does not mean you're supposed to switch to 16-bit mode before editing 8-bit data. If the image already is in 8-bit format then you can leave it there; going into 16-bit mode from 8-bit is pointless. [EDIT: This is not generally correct---please read the following posts.]
But if it is in 16-bit mode, then by all means do your editing of tones, colours, and contrast first (profile conversions, too) and switch down to 8-bit mode later.
Any better approach that won't mess with color or saturation?[a href=\"index.php?act=findpost&pid=164880\"][{POST_SNAPBACK}][/a]
I prefer to lighten up my images for print through the Screen blending mode. Either flatten your image or create a new top-most layer and merge all visible layers into it. Then duplicate the top-most layer and set the blending mode to Screen. Reduce the opacity to somewhere between 5 % and 25 %; 15 % seems to be a good starting point for most cases. The Screen blending mode will lighten up the image in a very natural-looking way, and will affect shadows more than highlights.
You
can achieve exactly the same result (including the opacity reduction) purely via Curves if you know how---but via the Screen blending mode it's far easier IMHO.
-- Olaf