Paint Shop Pro support - PSP 7 Selection not exact

Author

PSP 7 Selection not exact

Joseph Crain

2004-10-14, 7:16 pm

When using the selection tool (Selection Type: Rectangle) there is a
'guide' box that changes size during the click and drag operation.
Very often the final selected 'marquee' area is differs from the
'guide' by one pixel. Extremely frustrating! Usually I have to try
over and over again to get a selection that matches the area I need.

** I have antialias UNCHECKED
** I have feather set to 0

Does it not make sense the the final size of the selection should
match that of the guide?

Fred Hiltz

2004-10-14, 7:16 pm

Joseph Crain wrote:
> When using the selection tool (Selection Type: Rectangle) there
> is a 'guide' box that changes size during the click and drag
> operation. Very often the final selected 'marquee' area is
> differs from the 'guide' by one pixel. Extremely frustrating!
> Usually I have to try over and over again to get a selection that
> matches the area I need.
>
> ** I have antialias UNCHECKED
> ** I have feather set to 0
>
> Does it not make sense the the final size of the selection should
> match that of the guide?

It does. Make sure that you are viewing at 100% zoom. Otherwise, the
pixels on the screen do not match the pixels in the image. For
example, at 25% zoom, after you move the marquee, PSP must decide
which of four image pixels you intend.
--
Fred Hiltz, fhiltz at yahoo dot com

fugitive

2004-10-14, 11:15 pm

On Thu, 14 Oct 2004 18:05:11 -0400, "Fred Hiltz" <not@home.ca> wrote:

>Joseph Crain wrote:
>
>It does. Make sure that you are viewing at 100% zoom. Otherwise, the
>pixels on the screen do not match the pixels in the image. For
>example, at 25% zoom, after you move the marquee, PSP must decide
>which of four image pixels you intend.

Good answer, as I had none.

Joseph Crain

2004-10-21, 7:14 am

"Fred Hiltz" <not@home.ca> wrote in message news:<q4OdnUB0IKaGZfPcRVn-2A@adelphia.com>...
> Joseph Crain wrote:
>
> It does. Make sure that you are viewing at 100% zoom. Otherwise, the
> pixels on the screen do not match the pixels in the image. For
> example, at 25% zoom, after you move the marquee, PSP must decide
> which of four image pixels you intend.

I am assuming you mean 100% zoom means 10:1 zoom and not 100% of the
original image. This didn't produce any different results for me.
And regardless, PSP never has trouble discovering where to put the
guide box, which in my opinion (and I beleive the intended purpose of
the author) is the user's tool to decide the final size and position
of the selection.

Anyway, I have found the solution, and I have found out that the
behaviour mentioned in my first post most certainly is a bug in my
version, 7.0, becuase I am now able to predict it's behavior and it
goes like this:

The Bug
-------
During the click and drag operation of a rectangle select, the left
hand side of the bottom status bar shows some information about the
selection you are making, this is:

(left,top) -> (right, bottom) -> (width, height) [aspect_ratio]

When selecting an area, if I select an area which is an *odd* number
of pixels in height then the final height of the selection is reduced
by 2, where the top of the final selection is shaved by 1 pixel and
the bottom is shaved by 1 pixel.

The same is true for and odd width, where the left side of the final
selection is shaved by 1 pixel and the right side is shaved by 1
pixel.

Selecting and *even* number of pixels for width or height gives an
exact final selection for that dimension.

Heights or Widths of 1 pixel are unaffected.

The Solution
------------
The bug only occurs when you *do not* begin your click and drag from
the top,left of your selection and end on the bottom, right. So as
long as you drag from the top,left to the bottom, right everything
works fine.

Some Helpers
------------
After a selection is made, if it is not the correct size, you can add
to or subtract from the selection:
Hold Shift + click and drag to add an area to the selection
Hold Ctrl + click and drag to subtract an area to the selection
*The same bug applies to the selection of an area to be added or
subtracted.

Fred Hiltz

2004-10-21, 12:14 pm

Joseph Crain wrote:
> "Fred Hiltz" <not@home.ca> wrote in message
> news:<q4OdnUB0IKaGZfPcRVn-2A@adelphia.com>...
>
> I am assuming you mean 100% zoom means 10:1 zoom and not 100% of
> the original image.
>
> Anyway, I have found the solution, and I have found out that the
> behaviour mentioned in my first post most certainly is a bug in
> my version, 7.0,
[snip how to demonstrate it]

No, I meant 100% in its conventional sense of 1:1. The problem
appears here too. I have a faint recollection of it being reported
years ago here, not that it matters! Anyway, FWIW the selection
works right in PSP 8 and 9.
--
Fred Hiltz, fhiltz at yahoo dot com