cropping/masking a bitmap

[Mickie]

I was using Ross's wonderful freehand tool method of masking a photo (if you haven't already, see it here Ross's guest tut)when all of a sudden the main body of the photo was gone and I was left with a piece of sky. I realized that there must be some "rule" as to which part of the bitmap is masked...but I haven't been able to figure it out.

Anybody know?

Mickie

[Mickie]

I was using Ross's wonderful freehand tool method of masking a photo (if you haven't already, see it here Ross's guest tut)when all of a sudden the main body of the photo was gone and I was left with a piece of sky. I realized that there must be some "rule" as to which part of the bitmap is masked...but I haven't been able to figure it out.

Anybody know?

Mickie

[Ross Macintosh]

Thanks for asking. I've been using that method for years - and I suffer the same problem. (The part you wanted to keep disappears leaving you the portion you had intended to remove). Thanks to the 'undo' button it hasn't frustrated the heck out of me. I have never taken the time to figure it out. Hopefully someone has. I've long figured there is probably a simple explanation but I don't know what it is. I think it might have something to do with how many nodes there are on either side of the freehand edit line you've applied. I find it works best if you just 'snip' off small bits at a time - and gradually carve it to the shape you want. Because the 'small snip' method works reasonably predictably, I haven't thought to post the question. Thanks Mickie for doing so. I too would like to know what's up with it...

Regards, Ross

<a href=http://www.designstop.com/>DesignStop.Com</a>

[ajreed]

I might know the answer if only I understood the problem. Now and again Xara surprises me, but there's generally a sound reason behind it.

I was always getting the stack order wrong when doing 'intersects' and ending up with the wrong fill. Now I learnt just how to do it predictably, and i suspect your little problem also has a simple rule that you are unwittingly violating.

So - some more detail please?

Alan

[Ross Macintosh]

Okay Alan of East Sussex - Draw a filled shape using the shape editor tool. Now you can use the freehand tool to edit that shape. To do so, select the shape and then bring the freehand tool's cursor close to the edge of the shape. As you do you'll notice the cursor changes to include a little wavy 'tilde' symbol. That is good - it means you are in freehand edit mode upon holding down the mouse button (do that). Move the cursor until it intersects again with the edge of the shape and the 'tilde' reappears - at which point, if you release the mouse button, part of your shape will have been swiftly edited away. Mickie's question related to the fact that (unless there's a trick) it is hard to predict which side of the freehand edit line will be edited away from the original shape. Try it and you'll see what we mean - try and predict which side will be edited...

Regards, Ross

<a href=http://www.designstop.com/>DesignStop.Com</a>

[Christine Farrelly]

I think you'll find that it is to do with the number of nodes left, Xara appears to leave the shape with the most nodes.

Christine

[heimo]

Thanks to Ross's guest tut! Here are some ideas to make it easier (to me?)
Draw a new shape over the importet bitmap. It could be a Help to apply transparence to look behind for editing the shape for a closer fit.
Then
You give Xara the advice to "arrange-combine shapes-lice(cut)shapes!" and You get the masked object. After this, you can apply feather region
to loose all the small not wanted spots around.
Put dow a new Background an this was it..

This Way shold be much faster than editing the Photo by itself with the shape - Editor- Tool.

http://www.salzburg.co.at/hmooslechn...finsternis.jpg

[ajreed]

I played along the lines you suggested and reach the conclusion Christine is quite correct in that it is the part containing the most nodes that is the survivor.

I have proved this fairly conclusively by starting with a fairly complex shape, counting the nodes either side of the intended connect points, made the new stroke, and what was expected actually happened. Hit Undo. Used the editor tool to add a few nodes to the section that contained the lesser count (to increase its count above that of the other segment) then did EXACTLY the same modify stroke again. This time the OTHER portion of the blob disappeared, but consistently the survivor was again the section with the greatest number of nodes.

Yes - you guessed - I then created a blob with an even number of nodes - and quite consistently when you edit through the middle (equal node count either side of your intended connection points) Xara quite repeatedly blows away the right hand side. Tried this with blobs created with a clockwise stroke as well as an anti-clockwise stroke, no difference. There is probably a technical way of describing 'the right hand side' but thats the way it looked to me.

I have to say I have never encountered the surprise disappearance of the part you were hoping to retain, but I guess with a few hundred nodes on a complex shape, when you make a radical change, you are obviously risking making a modification where you unwittingly happen to divide your existing shape just the OTHER side of the node count balance. Hence the unexpected effect. Still - as you say there is always the Undo button for these rare occassions!

Never happens when your mod increases the shape, only when trying to nibble bits out of it.

So there - Xara is behaving consistently - although I bow to Christines' perception in identifying exactly the criteria Xara was considering. Now that it seems clear, when it does happen we all might now appreciate why, and just repeat the mod again aware of and able to adjust to this rare event.

It would be nice if someone from Xara Ltd could actually confirm this diagnosis, because I have convinced myself I am right [img]/infopop/emoticons/icon_biggrin.gif[/img]

Alan

[Mickie]

Christine and Alan...sounded good to me. So I started experimenting. I added a node to a partially masked photo. The section I wanted to keep had 4 nodes. I was stripping off a piece with three nodes...but was left with the wrong piece.(Illustration attached)


Maybe there are hidden nodes in there [img]/infopop/emoticons/icon_eek.gif[/img]

Mickie

[ajreed]

can you post the .xar file of your bird before you performed the snip illustrated above.

As I said I had convinced myself but you seem able to prove black is white.

I really would love a chance to try my test on your image.

Alan