Mike Chaney's Tech Corner

How can I change 100% white down to 98% (or whatever works) without effecting the rest of the print (as described here - http://technology.lenswork.com/2010/04/chasing-highlight-tones.html). I have tried levels and curves but they both appear to effect all of the print. I have not printed yet (I just ordered Profile Prism and will wait until there are proper ICC files in place) so I have not checked actual prints.

Hi,
He says on that link "At the very highlight end of the scale, photographers often don't mind having a perfectly pure white tone in their prints. We call these 8-bit RGB 255,"
I would not agree with that unless it's in a very small area like a spot reflection. I make great effort not to have blown highlights that give 255,255,255  :o
Back the main question:
You can easily do it with curves but you need to pin most of the curve to the original straight line. Some curve editors move other parts of the curve a considerable amount when one particular point is moved. The QU editor does this to a small extent so "pinning" is still required.
See the attached example, a curve with the top end flattened in an exaggerated way to illustrate this. I couldn't find an image with a large area of pure white!  ;)
The original "white" was 235,244,242 indicated by the red dot on the curve. The filter preview shows the effect where the curve above RGB value 192 has been reduced. In practice I assume you would flatten above say 245 or 250. You would lose contrast in that range of course.
Terry

I didn't read that article, but it sounds like lowering the 255 white point a tad.
It's really easy to do that if that's what you are trying to do.

In Curves, type a 16 into the location box, which makes a 255 appear in the input, and the output boxes.
Simply type a 250 in place of the 255 in teh output box.

I hope that's what the gentleman wanted.
Fred

That works perfectly, thanks.

I didn't realize I had to select the Preview window every time before pinning a point to a line when it isn't being moved (4, 8, 12 in this case). I saw that seventeen could be added but assumed I was misunderstanding the help file and there was a limit of one.

By the way I have several photographs to print that were originally edited for the web. I liked using photos that appeared edgeless on a white background so took them to the top and saved them so that is why there are some 255,255,255s in the group.

You don't have to select the preview to make any changes to a curve. I have it set to auto pop up whenever any change is made in the editor. See the Editor view menu and below.
Terry.

Terry,
I think he can set the white point in CURVES and then when clearing out of the editor, (with a number of images in the queue with the same need), he can tell Qimage to Apply to all the images in the queue.

Fred

Fred & jwwbrennan,
Good point  ;)
The other way would be to use a print filter by applying the curve to one image (no other filters at all), and save the filter with a meaningful name. When the Print Filter box is ticked, browse to that filter and select it.
That way, the image is not affected, only the print. 8)
Terry

That's a great thought!
Never thought of it that way.
Many people show their stuff at club meetings on a screen through a projector.
The prints, on the other hand might need something else.

Fred

Qimage is obviously so well thought out. Being able to keep just the originals at the original size and filter for device or even for media is ideal.

Thanks again guys for your expertise.

Well you (I) live and learn, just tried that out on one of my old images and ofcourse it works fine.

Another one for the armory.

jeff