How about something like :

duplicate layer desaturate
invert
slight blur
adjust opacity
merge

HTH

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On Wed, Apr 1, 2009 at 6:32 PM, paperaussie wrote:

Can any experienced Gimp users tell me how the process described in Ron Bigelow's article can be reproduced in Gimp most efficiently?

http://www.ronbigelow.com/articles/contrast/contrast.htm http://www.ronbigelow.com/articles/contrast/contrast.htm

Looks like a quite handy process to optimise some photos. I think I sort of could reproduce it with layers but I couldn't figure out if it is possible to follow these instructions with channels.

The procedure in GIMP is virtually identical. I'll paste the most relevant part here, adjusted for GIMP:

---

A selection of the entire image is created by choosing Select/All. The image is now copied by choosing Edit/Copy. A new channel is created by clicking on the Create new channel icon at the bottom of the Channels dockable (see Figure 5). The channel should be renamed the Contrast channel. The image is now pasted into the Contrast channel by selecting that channel and choosing Edit/Paste, going to the Layers dockable and clicking the Anchor icon. Next, it is necessary to invert the black and white image by choosing Colors/Invert.

---

Francesco Scaglioni wrote:

How about something like :

duplicate layer desaturate
invert
slight blur
adjust opacity
merge

Placing the top layer in divide mode is also very useful. Also try Overlay or Soft light. All this is much simpler than the method suggested by the original site, which seems an overkill.

On Wed, Apr 1, 2009 at 10:53 PM, Olivier Lecarme

Placing the top layer in divide mode is also very useful. Also try Overlay or Soft light. All this is much simpler than the method suggested by the original site, which seems an overkill.

Agreed. If I was doing this, I would not use channels at all, and I'd hardly use layers.
I would:
1. Edit->Copy the image
2. Enter QMask mode
3. Edit->Paste, and Anchor
4. Colors->Invert
5. Leave QMask mode
6. Edit->Copy
7. Edit->Paste
8. Convert the floating layer to a normal layer 9. Adjust the new layer
10. Merge or flatten when done.

Quoting paperaussie :

Can any experienced Gimp users tell me how the process described in Ron Bigelow's article can be reproduced in Gimp most efficiently?

http://www.ronbigelow.com/articles/contrast/contrast.htm

The following link is to a short screen capture of how that might be done in GIMP I use a similar technique quite often when adjusting highlights and shadows. There is no sound but the video should be easy to follow (I apologize for the jumpy pointer; my optical mouse died and I had to use a trackball).

http://flashingtwelve.brickfilms.com/GIMP/Temp/masking.ogv (OGG Theora 2.7Mb)

1. Drag your original layer over to the Channels Dialog and drop it, creating a new channel.
2. Hide the channel by clicking on its "eyeball" icon. 3. Return to the Layers Dialog.
4. Duplicate your original layer and increase its gamma using the Levels filter.
5. Add a layermask to the duplicate layer, initializing it to the inverted channel produced by Step 1. 6. Add a bit of Gaussian blur to the layermask (optional). 7. Adjust the opacity of the duplicate layer to obtain desired result.

Step 4 is not necessary if you already have an "overexposed" version of the original layer (created from a HDR RAW file), as was the case in the tutorial you linked to.

Saul:
You said

1. Drag your original layer over to the Channels Dialog and drop it, creating a new channel.

In your video, when you drag the image from the layer dock up to the channels dock your cursor has a '+' sign inside the _
|+ ... when I do it I have no plus sign and when the channels dock opens and I drop the dragged item just disappears without raising a new channel.

I'm using 2.6.6 on Windows XP. I tried modifier keys Shift and Ctrl and Shift+Ctrl just in case but can't get the '+' sign to appear in the cursor and more importantly can't get the auto-creation of a new channel.

Is this a bug or is there something I'm missing?

saulgoode@flashingtwelve.brickfilms.com wrote:

Quoting paperaussie :

Can any experienced Gimp users tell me how the process described in Ron Bigelow's article can be reproduced in Gimp most efficiently?

http://www.ronbigelow.com/articles/contrast/contrast.htm

The following link is to a short screen capture of how that might be done in GIMP I use a similar technique quite often when adjusting highlights and shadows. There is no sound but the video should be easy to follow (I apologize for the jumpy pointer; my optical mouse died and I had to use a trackball).

http://flashingtwelve.brickfilms.com/GIMP/Temp/masking.ogv (OGG Theora 2.7Mb)

1. Drag your original layer over to the Channels Dialog and drop it, creating a new channel.
2. Hide the channel by clicking on its "eyeball" icon. 3. Return to the Layers Dialog.
4. Duplicate your original layer and increase its gamma using the Levels filter.
5. Add a layermask to the duplicate layer, initializing it to the inverted channel produced by Step 1. 6. Add a bit of Gaussian blur to the layermask (optional). 7. Adjust the opacity of the duplicate layer to obtain desired result.

Step 4 is not necessary if you already have an "overexposed" version of the original layer (created from a HDR RAW file), as was the case in the tutorial you linked to.

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Quoting Alec Burgess :

Saul:
You said

1. Drag your original layer over to the Channels Dialog and drop it, creating a new channel.

In your video, when you drag the image from the layer dock up to the channels dock your cursor has a '+' sign inside the _
|+ ... when I do it I have no plus sign and when the channels dock opens and I drop the dragged item just disappears without raising a new channel.

Just to be clear, after the Channels Dialog is raised (this feature thanks to Michael Natterer :) ), you must move the pointer down to the "channels" section of the dialog (as opposed to the "components" part at the top with the red, green, and blue components). The "+" symbol should appear when the pointer is hovered in the droppable region -- if you had some channels already there then the "+" would only appear when you are between channels (there would also be a horizontal line similar to what appears when dropping layers in the Layers Dialog).

I'm using 2.6.6 on Windows XP. I tried modifier keys Shift and Ctrl and Shift+Ctrl just in case but can't get the '+' sign to appear in the cursor and more importantly can't get the auto-creation of a new channel.

I do not use Windows so I doubt I can be of much help. You should check to see if you can drag-n-drop layers in the Layers Dialog to reorder your layerstack (instead of a "+" symbol, you will see an arrow because you are not copying the layer, but moving it).

You should also see if, in the Channels Dialog, you can drag one of the components (red, green, or blue) down from the top and drop it in the channels list. If you have problems doing either of these then it is possibly owing to a bug in the Windows version of GIMP.

Thanks Saul. (Leaving text below in case this s/b the basis for a bugreport ...)
a) I can drag and drop in the Layers dialog - but never see the '+'-sign in the cursor.
b) In your video (I stepped through it frame by frame so I'm pretty sure I have this correct) as soon as you grabbed the layer and moved it up to the channels icon to open the channels dialog the '+' sign appeared and (I think(?)] was visible until you dropped it "below the line - below the components section - into the channels section.

When I do it (again Windows XP, same in both GIMP 2.6.6 and GIMP 2.7 r28070) the '+' sign never appears while dragging in the image dialog and only appears when dragging in the channels dialog if I position my cursor to the right of where a fairly short channel name would appear - or if none yet, to the right of where it would be. (If description is 10 characters (say) "background copy" the "+" sign appears when cursor is over the 'c' in "copy" or further right - otherwise it is not shown). When '+' displayed drop will be successful otherwise it fails. .
When I was first trying to follow your description I didn't have my cursor far enough right and first time I managed to do it had confused myself into thinking it was a matter of how close cursor was to the separator line :-(

For improved discoverablity suggest that the '+' sign s/b added to drag-drop anywhere its legal to drop and in particular only be removed in the Channels dialog when cursor is over the components section but reappear when cursor is *anywhere* below the line. I *think* but not sure about this, that '+' sign should appear when cursor is over the "Channels " icon allowing drop there - which should automatically drop it in the same place that a new channel would be created if user keyed Shift+[New] button.

can anyone confirm/refute above using Linux/Mac/Windows build?

btw: Once I got the above straight your "recipe" worked great on the sample image.

saulgoode@flashingtwelve.brickfilms.com wrote:

Quoting Alec Burgess :

Saul:
You said

1. Drag your original layer over to the Channels Dialog and drop it, creating a new channel.

In your video, when you drag the image from the layer dock up to the channels dock your cursor has a '+' sign inside the _
|+ ... when I do it I have no plus sign and when the channels dock opens and I drop the dragged item just disappears without raising a new channel.

Just to be clear, after the Channels Dialog is raised (this feature thanks to Michael Natterer :) ), you must move the pointer down to the "channels" section of the dialog (as opposed to the "components" part at the top with the red, green, and blue components). The "+" symbol should appear when the pointer is hovered in the droppable region

Quoting Alec Burgess :

For improved discoverablity suggest that the '+' sign s/b added to drag-drop anywhere its legal to drop and in particular only be removed in the Channels dialog when cursor is over the components section but reappear when cursor is *anywhere* below the line. ...

What you describe is how GIMP _should_ work, and how it _does_ work on my machines (GNU/Linux, GIMP 2.6.7). I have also tested on a friend's Windows machine running GIMP 2.4.6 and the behavior is as you describe.

... I *think* but not
sure about this, that '+' sign should appear when cursor is over the "Channels " icon allowing drop there - which should automatically drop it in the same place that a new channel would be created if user keyed Shift+[New] button.

This is not how GIMP currently behaves, but might be a reasonable enhancement request. Personally, I don't think it would be that beneficial (no offense) and should require examination of other drag-n-drop functionality from a UI perspective (e.g., if a color is dropped on the Text Tool Options tab, does the text color change). In any event, this should not currently be considered a bug.

I believe that you should post the anomalous behavior you are experiencing to the developer's mailing list, or submit a bug report. You should be able to drop a channel _anywhere_ within the channel list frame of the Channels Dialog and your inability to do so would seem a regression.

If you could install an older version of GIMP to verify my findings with 2.4.6 on Windows, that should prove helpful. (If you go much older than 2.4.6 then you will need to have the Layers Dialog and the Channels Dialog in different docks; because the "auto-raise tab" functionality had not yet been implemented.)

Gimp newbie here.

How do you enter QMask mode?

Thanks!

----- Original Message ---

On Wed, Apr 8, 2009 at 8:50 AM, Fatbob wrote:

Gimp newbie here.

How do you enter QMask mode?

"the left-bottom button in the image window"

http://docs.gimp.org/en/gimp-using-quickmask.html

David Gowers wrote:

On Wed, Apr 8, 2009 at 8:50 AM, Fatbob wrote:

Gimp newbie here.

How do you enter QMask mode?

"the left-bottom button in the image window"

http://docs.gimp.org/en/gimp-using-quickmask.html

Or the Shift+Q key.

Thanks!

----- Original Message ---