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trouble cropping active layer

Sep 4, 2014, 18:28
Post: #1
trouble cropping active layer
Hello! ( i'm new and foolish in this environment.)

I am trying to remove a background on an active layer. i see a lot of options:

I tried just erasing. and it won't erase unless i merge. but i don't want to merge because i can't "undo" it later. and the active layer is over 2 layers and i want to erase down to each different layer...one is mostly under the top of active layer and one under the bottom. and so i can't find an effective application of the tools. i'm not sure why it won't just erase down to what shows below it on different sections.

i could also do some of the removal work by using the fuzzy wand or lasso (i think) and circling most of what i'd like to remove. but i just can't get it to remove the background instead of the foreground (when i hit delete, the part INSIDE the drawn border disappears in sted of outside). i tried to use the foreground select tool but i guess that's not appropriate for this task.

same with the lasso...i can't figure out how to select the part i want to keep.

not sure how relevant this is but at one point i had it at a bigger size to erase background. and it did erase but down to a white background...and when i had started the project by erasing the previous layer over the first layer, it did what i wanted...it left me with the image below what i erased.

so without merging, i don't know how to erase. it would be easier to work if i scaled it bigger again but i still have the same problem with this white background being left behind.

i'm trying to learn how/when to utilize alpha channels and select "none" 's but so far i havn't made any of those selections relevant to accomplishing this.

i've watched some tutorials to get this far and read some sections of user manual and older forum threads but can't find anything that quite describes this scenario.

even a lead with what keywords i'm missing to a more specific tutorial would be helpful. but if anyone can suggest things, it's much appreciated!

best... (and thnx!)...
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Sep 4, 2014, 18:48 (This post was last modified: Sep 4, 2014 18:50 by rich2005.)
Post: #2
RE: trouble cropping active layer
Quote:I tried just erasing. and it won't erase unless i merge. but i don't want to merge because i can't "undo" it later. and the active layer is over 2 layers and i want to erase down to each different layer...one is mostly under the top of active layer and one under the bottom. and so i can't find an effective application of the tools. i'm not sure why it won't just erase down to what shows below it on different sections.

You can not have an active 2 layers. One active layer at a time.
If you want to save them, set them as the only visible layers then use Layer -> New Layer from Visible and work on that. Turn the visibility of the 2 original layers off so they do not get in the way.

Selections are applicable to all layers so you can make a selection using one layer and use it on another layer but you must be on the other layer (ie it is active)

Quote:..i'm trying to learn how/when to utilize alpha channels and select "none" 's but so far i havn't made any of those selections relevant to accomplishing this.

An alpha channel enables transparency, generally when you create a new layer the default is transparent. Transparency lets you make "holes" in a layer and see what is below. If there is nothing underneath to show then Gimp denotes transparency with a checker board pattern.

** https://www.gimp-forum.net/ now answering questions**
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Sep 4, 2014, 19:26
Post: #3
RE: trouble cropping active layer
(Sep 4, 2014 18:48)rich2005 Wrote:  
Quote:I tried just erasing. and it won't erase unless i merge. but i don't want to merge because i can't "undo" it later. and the active layer is over 2 layers and i want to erase down to each different layer...one is mostly under the top of active layer and one under the bottom. and so i can't find an effective application of the tools. i'm not sure why it won't just erase down to what shows below it on different sections.

You can not have an active 2 layers. One active layer at a time.
If you want to save them, set them as the only visible layers then use Layer -> New Layer from Visible and work on that. Turn the visibility of the 2 original layers off so they do not get in the way.

Selections are applicable to all layers so you can make a selection using one layer and use it on another layer but you must be on the other layer (ie it is active)

Quote:..i'm trying to learn how/when to utilize alpha channels and select "none" 's but so far i havn't made any of those selections relevant to accomplishing this.

An alpha channel enables transparency, generally when you create a new layer the default is transparent. Transparency lets you make "holes" in a layer and see what is below. If there is nothing underneath to show then Gimp denotes transparency with a checker board pattern.

NEW REPLY:

thnx for the tips...good for my general learning and future reference.

but it doesn't quite help with THIS obstacle (which i know i had trouble explaining effectively)

i can't get the active layer (i know there's only 1) to erase down to the layer visible below it. i WANT to see those layers in their current opacity.

i wonder if it had to do with that i first erased leaving the layer scaled larger than i would later re-size it to. and so the color in the image DID erase but it left a white background. so i have this object i want to be visible but surrounded by a white background now.

so i scaled it down to desired size...this entire image block with the the desired object surrounded by white background--which i want to remove by any method that'll work.

i can not make it erase the white background and show the inactive layers below it.

so...i'd like to know why that won't work but for the time being, would settle for being able to crop this active layer...to remove this background. and when i circle it with the fuzzy wand or the free-select tool and hit delete, it makes the object in the center of the block that's the layer disappear instead of the surrounding white background...even if i try it with the foreground tool too.

i'm assuming i'm not trying the needed steps in an appropriate order...i'm SURE it's all possible. i watched tutorial producers perform similar technique.

so i'd prefer to get this white background to erase so i'm not moving this whole square image layer. but at least cropping would get me closer if i could get it to remove the area OUTSIDE the drawn selection.

hope this made my obstacle more clear. thnx again for the consideration.
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Sep 4, 2014, 20:00
Post: #4
RE: trouble cropping active layer
Packing in for the night, but before I go, some really-really basic erasing.

You can add an alpha channel for transparency Layer -> Transparency -> Add Alpha channel.
note that in the layers dialog, a layer name without alpha is shown in bold
screenshot http://i.imgur.com/IYolT0h.jpg

Now start erasing and it looks like this, transparency in the layers dialog shows as the checker board pattern.
screenshot http://i.imgur.com/lOimXz9.jpg

Exactly the same image but with the alpha channel removed and now it is white, which you have already found out.
screenshot http://i.imgur.com/zspupFb.jpg

** https://www.gimp-forum.net/ now answering questions**
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Sep 4, 2014, 20:27
Post: #5
RE: trouble cropping active layer
very good share...thnx for the effort.

i havn't completed my task yet but played around with it on a smaller scale and between your examples of alpha and learning about using "invert" in another tutorial (for my cropping issue) i think i found most of the missing steps in my strategy.

i'm sure this will be a big part of everything i build on as i try to learn. thnx for your patience with my inexperience in this environment and of course hope the post will help others!
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Sep 4, 2014, 20:37
Post: #6
RE: trouble cropping active layer
Welcome bugsinherteeth,
Sounds like you have your answers for now but ask as many questions as you need to.
Always someone willing to assist Wink

Tip: A quick visual way to tell which layers have an Alpha Channel is that the layer names are in 'Bold' font for those without and 'Non Bold' font shows they have an Alpha channel.
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