On 15/03/17 19:53, bsmile wrote:

Three questions,

(1) can I group the layers together and then request autocrop? right now, I seem to have to merge layers to be one to request autocrop. But that prevents me from the ability to do changes as needed.

(2) After I merge to just a single layer, it seems autocrop can crop the upper and bottom whites well, but not the left and right white, do you see the same thing or any wrong I did?

(3) It seems gimp does not provide convenient tools like arrow etc, so I basically copy/paste the arrows from powerpoint here, the issue is, it seems the color cannot be copied. Is there way to deal with that?

Still a quite newbie, thanks for your kind help!

Attachments: * http://www.gimpusers.com/system/attachments/515/original/fermisurface_a.xcf

1) Image>Autocrop image, once you have fixed 2) on the two layers.

2) You white background is not uniform it contains pixels with 253 instead of 255,

http://imgur.com/zHn0KH9

... and autocrop only works with completely uniform backgrounds. You can fix this with "Levels", dragging the right hand of "Input" towards value 250 (or anything left of the line at value 253 in the histogram).

On 16/03/17 00:22, bsmile wrote:

1) Image>Autocrop image, once you have fixed 2) on the two layers.

2) You white background is not uniform it contains pixels with 253 instead of 255,

http://imgur.com/zHn0KH9

... and autocrop only works with completely uniform backgrounds. You can
fix this with "Levels", dragging the right hand of "Input" towards value
250 (or anything left of the line at value 253 in the histogram).

Thanks for the explanation, but please be more specific where to locate the option of value to be revised?

I right clicked my mouse to bring up colors->levels->input levels, output level, I changed the value to 250, and then ok, then layer->autocrop layer, but no difference, I right click my mouse again to input levels, it is still 255, like never been modified before.

If you use Windows>Dockable dialogs>Histogram the right of the histogram has two vertical lines, which indicate that that you have pixels with value 253 as well as pixels with value 255. You should also see these two lines in the histogram shown in the Levels tool. In Levels, if you drag the right handle of the input (top bar) to the left of the two lines (around 250), then everything bigger that the indicated value becomes pure white, so this should change your pixels with value 253 to pure white.

To answer your third question, there are a number of scripts that will draw arrows, one of which is described at:

http://registry.gimp.org/node/28566

The script itself can be downloaded from:

http://www.programmer97.talktalk.net/Files/arrow.zip

The arrows are drawn in the currently selected foreground colour.

Three questions,

(1) can I group the layers together and then request autocrop? right now, I seem to have to merge layers to be one to request autocrop. But that prevents me from the ability to do changes as needed.

(2) After I merge to just a single layer, it seems autocrop can crop the upper and bottom whites well, but not the left and right white, do you see the same thing or any wrong I did?

(3) It seems gimp does not provide convenient tools like arrow etc, so I basically copy/paste the arrows from powerpoint here, the issue is, it seems the color cannot be copied. Is there way to deal with that?

Still a quite newbie, thanks for your kind help!