MAKING A PERFECT ELLIPSE FOR LAYER MASK

Apuleius · **Joined:** Sep 06, 2020 **Posts:** 20

GIMP Version: 2.8.14
Operating System: Linux
GIMP Experience: Basic Level

I want the clock tower to come out of the coffee cup.

I made a layer mask, so that I could paint out the lower part of the tower.
what I found was the the lip of the cup, which is a perfect ellipse, is very hard to paint. It looks bad.

but I know GIMP has an ellipse selection tool.
Is there a way to place the ellipse around the lower part of the tower
then turn it at an angle
then erase the part we don't want
to exactly match the lip of the cup?

sallyanne · **Posted:** Sat Aug 28, 2021 12:44 am **(#2)**

Position your tower as you want it first. Make sure you only have the 'tower' layer mask selected and you should be able to do it.
Make your selection so it goes along the cup lip and right around the tower, fill your selection in with colour white if using a black (fully transparent) mask
I did a simple mortar and pestle out of the cup in g'mic, using a mask.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4752

YOU CERTAINLY DON'T WANT A PERFECT ELLIPSE BECAUSE THERE IS SOME PERSPECTIVE IN THE CUP. THIS SAID:

CREATE AN ELLIPSE SELECTION ROUGHLY WHERE YOU WANT IT
USE THE UNIFIED TRANSFORM TOOL IN "TRANSFORM: SELECTION" MODE (RED SQUARE ICON) TO TWEAK YOUR ELLIPSE AND ADJUST IT TO THE LIP OF THE CUP. YOU MAY HAVE TO DE-SELECT SOME "CONSTRAIN" SETTINGS IN THE TOOL (SCALE, ETC...).
WHEN HAPPY WITH THE FIT, "COMMIT" THE TRANSFORM .

Attachment:

Unified.png [ 478.17 KiB | Viewed 2587 times ]

sallyanne · **Posted:** Sat Aug 28, 2021 4:15 am **(#4)**

@ofnuts, you are correct about perspective for the whole ring. What if only the closest cup lip was selected though plus the top of the tower - Wouldn't they beable to mask it by filling the selection in with white then?

Imagine you still have your seperate layers - do what I said before
If you make a selection along your cup rim up to the top of the tower (you may have to play with it a bit to get it along the lip but you will not have to move it aound after, and it will not matter if you go outside of the cup), after you position your tower and add a black mask over your tower layer. Making sure you only have the mask selected then fill it with white. That will show the top of your tower again only in that selection.

rich2005 · **Joined:** Mar 04, 2011 **Posts:** 2435

@Sallyanne That is possible although you need to concentrate on fitting the lower part of the ellipse as well as the overall size to include all of the layer mask.

Quote:

I made a layer mask, so that I could paint out the lower part of the tower.
what I found was the the lip of the cup, which is a perfect ellipse, is very hard to paint. It looks bad.

If you concentrate on the curve of the rim, then use the various selection modes for a layer mask Layer -> Mask -> (various selection modes). Using intersection mode gets a partial selection. Invert it and just paint it out. I can just get it into 60 seconds

https://i.imgur.com/Lf9DC6g.mp4

I would be inclined not to use an elliptical, a path and path to selection might be easier than rotating / sizing that ellipse..

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4752

rich2005 wrote:

I would be inclined not to use an elliptical, a path and path to selection might be easier than rotating / sizing that ellipse..

That was my first shot at it, but it turned out to just add the "Select > To path" and "Select > From path" steps with no improvement in the core steps.

Apuleius · **Joined:** Sep 06, 2020 **Posts:** 20

thanks to
thanks to
sallyanne
rich2005
ofnuts
for your contributions.

--OP

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