Excuse the ignorance folks, but could someone please explain to me what a 'control point' is. Thank you.

Nikon have this "Upoint technology" to selectively make local bright/contrast/RGB etc adjustments around a variable diameter circular zone based round the "control point", or in the above example to select a neutral point which can be dragged around a bit to get the best position & effect.

In their blurb:
"Use the new Color Control Points to control color and lighting selectively, eliminating complicated processing and tedious manual selection"

Like DPP, NX can be used for .jpg & .tif images & there is a 30 day free trial download if you want a play. I got one day before the D80 and was already half-way to being a Nikonman before I even had the camera.(no loyalty eh?)

Interesting post Chris.

Mmmm. I have not checked this as I always save the whole processed frame as a Tiff and then crop in Photoshop.

I will place a grid on a tiff then check what happens to control points in NX on a crop.

Don

Duncan,

Following Chris's explanation here is what one looks like and an idea of its available adjustments.

Don

I inadvertently did a crop on a pic with some control points in a previous step. Although the points moved on the y axis, their effect remained at their original position.

I don't think Stephen's one moved on the x axis, again only y, so why its effect altered becomes an even deeper mystery. But the obvious thing to do is to do ones crop early on for the sake of safety as well as composition

The control point I commonly use it the neutral one where position is CRITICAL to its implementation. Other control points particular placed on the sky would not exhibit the issue as much.

I straighten then crop as my PC always converted to TIFF quicker with a cropped image, speed gain was proportionate to the severity of crop.

As promised.

To check the movement of Control Points including Black/White/Neutral I resized an image to 2000 wide. I then added a grid at 100 pixel spacing.

Three crop zones were added.
The crops were actually done on the white grid to ensure they were in exact units x 100 pixels. The colour marks being just inside the grid.

Control points were used in these samples, but tests show Black/White/Neutral points behave in exactly the same way when a crop is done after they have been placed. All movement of points on the image is a result of the selected crop.

These show quite conclusively that the points reference the top left of the image. On a crop all points maintain a reference to that position and do not move radomly.

Images attatched.

1) Resized copy of the test target.
2) Placement of control points on the uncropped image.
3) Yellow Crop
4) Green Crop
5) Purple Crop

Don

And most telling the one I could not get in the last post.

A random crop from near a midpoint, so essentially cropping out some points, but to include bottom right hand corner of the image. Notice the displaced Control Points. Quite telling when compared to the Yellow Crop.

Don

that all seems clear enough on the black/white/neutral, but just to fuzz it up a bit, these are the less exact results I reported before from an inadvertant late crop

The crop turned off, a cluster of colour control points on and by the sheep
http://www.worldphotographyforum.com...1&d=1196973341

The crop made, the cluster has dropped to the bottom, but the sheep area where they were still brightened as intended
http://www.worldphotographyforum.com...1&d=1196973421

with the crop turned on but the effect of the control points turned off, they are clustered down the bottom and the sheep pretty dark

http://www.worldphotographyforum.com...1&d=1196973113

If the crop is turned off, they spring back, but they are no longer alive for further editing as they should be, so still not a clever idea!

Chris,

If the crop is turned off the control points can be edited.
Editing any control point that is still visible after a crop will automatically turn the crop off for the edit and it then has to be checked to turn it on again afterwards.

I will see if I can do something on editing tomorrow but it will definately be by Saturday.

I see from your gallery you have been busy. :)

Don