getting control over Curves (CS2)

I've been using CS2 for a month or two. Before that I generally stuck with Paint Shop Pro, which handles curve adjustments much less aggressively than Photoshop. I have a couple of questions:

Is there a way to tell CS2 to stop adjusting the curve past existing control points? For instance, if there's a white point clip set 1/4 of the way into the Curves box, it's very annoying when the clipped portion of the line dips back into the box because of an adjustment farther down. Or vice versa--if I'm raising a steep shadow slope, I don't want the rest of the line to spike high or low in response.

Is there any way to get the curve control points any closer together than 4 levels on the input axis? They always merge or generate a "no can do" message.

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2...it's hard to tell whether Levels does the job, and it's difficult to control Curves to do this by hand. I should add that my math and optics knowledge here is limited to knowing how to plug input numbers into a gamma formula and get outputs; I won't know success when I see it. :)

Thanks for any help.
false_dmitrii

wrote:

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2

Until someone comes up with the correct answer, have you had a look in the Edit->Color Settings [sic] when you choose Custom RGB... in Working Spaces->RGB?

Andrew

i am kinda confused about what you want to do. first go to your color settings and choose adobe RGB (1998) and down further you can set your gamma to 2.2. now in curves, you know you can change your gride by cmd/cntrl clicking on the grid itseld. try cmd/cntr/ clicking on the part of the image you want to change and it will set a probe on your curve line and you can make local adjustments right there. keep in mind that change the "input "level ALWAYS increases contrast and changing the "output" level ALWAYS decreases contrast.
hope this helps,
carolyn
www.carolyncoffey.com

i forgot to say the you can limit you output by clicking on the white eyedropper and set the RGB amounts to around 8 each and clicking on the black eyedropper and "limiting" those values to around 248.

Andrew Morton wrote:

wrote:

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2

Until someone comes up with the correct answer,

It may not be the /correct/ answer, but in ImageReady there is a gamma adjustment available.

Andrew

wrote in message

I've been using CS2 for a month or two. Before that I generally stuck with Paint Shop Pro, which handles curve adjustments much less aggressively than Photoshop. I have a couple of questions:
Is there a way to tell CS2 to stop adjusting the curve past existing control points? For instance, if there's a white point clip set 1/4 of the way into the Curves box, it's very annoying when the clipped portion of the line dips back into the box because of an adjustment farther down.

Set your white point by moving the end point of the curve, instead of by adding a point to the interior of the curve. That way there will be no clipped portion of the line to dip back.

Or vice versa--if I'm raising a steep shadow slope, I
don't want the rest of the line to spike high or low in response.

This is a characteristic of the spline curve math used to generate the curve shape. Add a second point toward the middle to bend the rest of the curve back into place.

Is there any way to get the curve control points any closer together than 4 levels on the input axis? They always merge or generate a "no can do" message.

In certain situations, you may find Photoshop's pencil mode useful for detailed manipulations of an isolated part of a curve - for example when cleaning up a mask. In some versions of Photoshop you can make the curve window somewhate larger by clicking on an icon in the upper right or bottom right corner, depending on the version.

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2...it's hard to tell whether Levels does the job, and it's difficult to control Curves to do this by hand. I should add that my math and optics knowledge here is limited to knowing how to plug input numbers into a gamma formula and get outputs; I won't know success when I see it. :)

Andrew's answer is a good one. Create what is called a "false profile" in color settings with a gamma of 1.0 and assign it to your original scan, then convert to your working profile.
--
Mike Russell
www.curvemeister.com

Mike Russell wrote:

wrote in message

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2...it's hard to tell whether Levels does the job, and it's difficult to control Curves to do this by hand. I should add that my math and optics knowledge here is limited to knowing how to plug input numbers into a gamma formula and get outputs; I won't know success when I see it. :)

Andrew's answer is a good one. Create what is called a "false profile" in color settings with a gamma of 1.0 and assign it to your original scan, then convert to your working profile.

Andrew and/or Mike, can you guys elaborate on how to do this? I'm a little lost.

wrote in message

Mike Russell wrote:

wrote in message

What's the general method for creating curves outside of Photoshop for import? I'm specifically looking for a reliable way to convert a linear gamma 1.0 scan into gamma 2.2...it's hard to tell whether Levels does the job, and it's difficult to control Curves to do this by hand. I should add that my math and optics knowledge here is limited to knowing how to plug input numbers into a gamma formula and get outputs; I won't know success when I see it. :)

Andrew's answer is a good one. Create what is called a "false profile" in
color settings with a gamma of 1.0 and assign it to your original scan, then
convert to your working profile.

Andrew and/or Mike, can you guys elaborate on how to do this? I'm a little lost.

Go into your Edit>Color Settings, and create and save a custom RGB working space with a gamma of 1.0. Restore your original working space, and you'll find your new gamma 1.0 space as an option in the Assign Profile dialog.

--

Mike Russell
www.curvemeister.com