I think this is the area to post questions? I am having problems understanding what the Quick Mask is all about...even after whatching a vid on YouTube. Just what is this used for? My understanding at this point is "one can remove errors and defects in a photo with this tool. Any explanation and help would be appreciated.

Happy Holidays

--MN Mike

you use it for making selections
if you click on the quick-mask selection a red semi transparent color appears over your picture
you can paint now on this mask - white makes the mask transparent and black makes the transparency opaque again
when you switch off the mask, you get a selection (marching ants)

http://www.gimp.org/tutorials/Quickmask/

Yes as Esper says, it is very good too for removing backgrounds, if you make a mistake and go outside the lines, just paint it back in with the opposite color, change colors again and fix it.

As stated, the Quickmask is useful for editing your selection directly. If you were to do this without the Quickmask, the steps would be something like the following:

• "Select->Save to Channel" - your Channels dialog should appear with the saved channel active and your selection appearing as grayscale. Any painting, filtering, or rendering performed will take place on this channel.
• Make the channel visible in the image window by clicking on the "eyeball" icon next to its thumbnail preview in the Channels dialog. The channel will be shown overlaid your original image at 50% opacity.
• "Select->None" - This eliminates the marching ants and permits you to paint (filter, render, ...) on the entire channel, not just the selected region.

• Paint in your image window to modify the channel. You want to paint in white to select a region, in black to unselect it. You may also run filters (for example, "Filters->Blur->Gaussian Blur" will have the effect of feathering the edges of your selection). While editing your channel, you can make a new selection and limit your editing to the new selected region (e.g., bucket fill, render a pattern, pixellize, ...).

• After you are done editing your channel, click on the button at the bottom of your Channels dialog to replace the selection with the contents of the channel.
• Click on the delete button at the bottom of your Channels dialog to remove the channel.
• Go back to your Layers dialog and continue editing your image.

The steps in green and blue are effectively what GIMP does when you enter and exit Quickmask mode respectively. Though entering Quickmask does not raise the Channels dialog, if you were to raise it manually ("Windows->Dockable Dialogs->Channels") then you would see the temporary channel (named 'Quick Mask'). Also, the default color of a saved selection is black while the default color of the Quickmask is set to red; though you can change these by right-clicking on the thumbnail preview in the Channels dialog or the Quickmask toggle button in the lower left corner of the Image window.

thanks for the info, saulgoode !
i never find much use for the save to channel option

i mostly save selections as a path and while i see its a good thing you can blur a channel, i dont know what do to with it

You can make a path from a selection; but this is not saving the selection. If you go selection->path->selection you don't get the same selection. Try this:

- create a circular selection
- create new layer, fill with white, and bucket-fill selection with 50% gray
- "Select/To path" and "Select/From path"
- create new layer, fill with white, and bucket-fill selection with 50% gray
- put the top layer in difference mode: the image is all black with a faint circle (remove the ants to see it): this is the difference between your two selections.



Things are much worse if the selection has any feathering.

@ofnuts, thanks for the info,
i did the little experiment and when i use the selection saved to a channel, i get a complete black layer
so that means a channel is more precise, right ?

A selection mask is a channel. when you save it to a channel you save an exact copy.