X7 setting crop boundary (rectangle)

[edwinn]

Recently installed X7U and notice (or may have noticed) some difficulty setting the CROP rectangle.

Many times its necessary to precisely crop an image to the edge of some boundary like a screen-cap from Google Earth satellite view. When zooming in to the UPPER-LEFT and LOWER-RIGHT corners, I try to DRAG the crop rectangle (CR) to position, but it jumps to another pixel.

What's the criteria for, or where does the CR 'snap' to when setting it? pixel centers? edges? Seems one has to 'drop' the corner of the CR on 'center' of the pixel above and to the left of the desired pixel edge (or slightly lower X,Y pixel values).

How hard does it have to be.. to set a CR to a pixel edge?


Sometimes it takes 2 or 3 trial & error attempts to 'drop' the corner, hoping it will 'land' on the desired edge.

-Ed

[Radim]

For better precision you can use rectagle tool and create vector object. Switch off border and set some transparency 50% or so. Then when selection is fine tuned create selection from vector object.

[edwinn]

For better precision you can..
* Use rectangle tool and create vector object,
* Switch off border and set some transparency 50% or so,
* Then when selection is fine tuned create selection from vector object.

That's very interesting! Can you describe step #2 in a bit more detail? switch off boarder? that means 'Foreground-Stroke' material property off?

I see now that in Properties, Units, the box "Snap to center of Pixel" is checked. So I unchecked it, and now cursor is reading out in 1/100 of a pixel when dragging rectangular vector ? or what unit? That's overkill for cropping to a unit-pixel, but interesting!!!

So it should be possible to set CROP RECTANGLE (not vector rectangle) to snap to the Pixel Edges? This is what's perplexing.

-Ed

[edwinn]

Here's another tidbit.

In Preferences, Units HELP...

it says: Snap vector objects to the pixel’s center

In the Vector coordinates group box, mark the 'Snap to center of pixel while moving' check box.

However I need the Crop Rectangle, or Vector Rectangle to SNAP to the Pixel edge, or pixel INTERSECTION if dragging diagonally.


It seems necessary to drag Crop Rectangle to the CENTER of the next lower pixel in terms of x,y coords.


That's the issue.

Thanks, this is actually fun!

[JoeB]

For better precision you can..
* Use rectangle tool and create vector object,
* Switch off border and set some transparency 50% or so,
* Then when selection is fine tuned create selection from vector object.

I see now that in Properties, Units, the box "Snap to center of Pixel" is checked. So I unchecked it, and now cursor is reading out in 1/100 of a pixel when dragging rectangular vector ? or what unit? That's overkill for cropping to a unit-pixel, but interesting!!!

So it should be possible to set CROP RECTANGLE (not vector rectangle) to snap to the Pixel Edges? This is what's perplexing.

-Ed

As a followup to your question, I'm wondering what advantage, if any, there is to having that "Snap to Center of Pixel When Moving" box checked by default, and what, if any, is the disadvantage of unchecking it.