RSS/Atom feed Twitter
Site is read-only, email is disabled

Gimp channel mixer

This discussion is connected to the gimp-user-list.gnome.org mailing list which is provided by the GIMP developers and not related to gimpusers.com.

This is a read-only list on gimpusers.com so this discussion thread is read-only, too.

22 of 22 messages available
Toggle history

Please log in to manage your subscriptions.

Gimp channel mixer Oxonian 28 Oct 16:25
  Gimp channel mixer programmer_ceds 28 Oct 16:48
   Gimp channel mixer Oxonian 28 Oct 19:05
    Gimp channel mixer Oxonian 28 Oct 19:30
     Gimp channel mixer Oxonian 28 Oct 20:23
      Gimp channel mixer Oxonian 28 Oct 20:33
       Gimp channel mixer programmer_ceds 29 Oct 08:18
       Gimp channel mixer rich404 29 Oct 08:25
        Gimp channel mixer Oxonian 29 Oct 08:46
         Gimp channel mixer Oxonian 29 Oct 09:15
          Gimp channel mixer programmer_ceds 29 Oct 11:44
          Gimp channel mixer Rick Kline 30 Oct 01:07
           Gimp channel mixer Oxonian 30 Oct 09:20
            Gimp channel mixer Oxonian 30 Oct 09:29
             Gimp channel mixer rich404 30 Oct 10:36
              Gimp channel mixer Elle Stone 30 Oct 11:06
               Gimp channel mixer rich404 30 Oct 11:43
                Gimp channel mixer Patrick Shanahan 30 Oct 11:59
                 Gimp channel mixer rich404 30 Oct 13:57
                  Gimp channel mixer Oxonian 30 Oct 16:36
                   Gimp channel mixer rich404 30 Oct 17:27
                    Gimp channel mixer Oxonian 30 Oct 17:38
2017-10-28 16:25:25 UTC (over 6 years ago)
postings
11

Gimp channel mixer

I'm trying to use the GIMP channel mixer to reverse the red and green channels in a TIF image. I'm using GIMP 2.9.6.

After swapping the channels etc. and hitting OK, all that happens is that a very small thumbnail appears in the top left corner of the main image. I can see that the channels have been reversed in the thumbnail, but the main image remains unaltered.

I cannot find a way to apply the changes to the main image, I'm very new to GIMP and image editing software, so I hope the solution isn't something any ten year old child could work out! Any help greatly appreciated

2017-10-28 16:48:53 UTC (over 6 years ago)
postings
121

Gimp channel mixer

Works for me using 2.9.7 portable used in multi-window mode (commit 1773cd9) from Partha's site (Windows 7 64-bit)

I just set the red in red to zero and the green in red to 1.0 and vice versa then pressed OK. I didn't see a thumbnail but the active image changed as expected whilst editing, if I had the preview selected, and was changed as expected when I clicked OK.

If this later version gives you the same problem could you list the exact steps that you are using and I will see if I can reproduce the problem.

If you have the preview option selected does the active image change when you alter the channel mixer settings?

I'm trying to use the GIMP channel mixer to reverse the red and green channels in a TIF image. I'm using GIMP 2.9.6.

After swapping the channels etc. and hitting OK, all that happens is that a very small thumbnail appears in the top left corner of the main image. I can see that the channels have been reversed in the thumbnail, but the main image remains unaltered.

I cannot find a way to apply the changes to the main image, I'm very new to GIMP and image editing software, so I hope the solution isn't something any ten year old child could work out! Any help greatly appreciated

2017-10-28 19:05:15 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Works for me using 2.9.7 portable used in multi-window mode (commit 1773cd9) from Partha's site (Windows 7 64-bit)

I just set the red in red to zero and the green in red to 1.0 and vice versa then pressed OK. I didn't see a thumbnail but the active image changed as expected whilst editing, if I had the preview selected, and was changed as expected when I clicked OK.

If this later version gives you the same problem could you list the exact steps that you are using and I will see if I can reproduce the problem.

If you have the preview option selected does the active image change when you alter the channel mixer settings?

2017-10-28 19:30:48 UTC (over 6 years ago)
postings
11

Gimp channel mixer

I now believe the problem lies with the importing of the image. I have been importing fresh images into GIMP, what I had not noticed was that the tiny thumbnail is there from the beginning, my image size is 6016x4000, the thumbnail image is about 150x100 in the top left.

When I import the image a dialogue box opens with the title "IMPORT FROM TIFF" The box shows two pages and asks if I want to import them as layers or images, I have been importing them as layers. the layers appear with the top layer labelled as page 1, and beneath it the main image labelled background. If I turn off page 1 the thumbnail disappears.

I thought the two images may be the result of my files being too large, they are 137MB, under preferences the max image size was set to 128MB, I upped this to 164MB but it has made no difference.
If I import the pages as images I get two images, one the full size image, the other a very small image, both identical.

2017-10-28 20:23:31 UTC (over 6 years ago)
postings
11

Gimp channel mixer

I now believe the problem lies with the importing of the image. I have been importing fresh images into GIMP, what I had not noticed was that the tiny thumbnail is there from the beginning, my image size is 6016x4000, the thumbnail image is about 150x100 in the top left.

When I import the image a dialogue box opens with the title "IMPORT FROM TIFF" The box shows two pages and asks if I want to import them as layers or images, I have been importing them as layers. the layers appear with the top layer labelled as page 1, and beneath it the main image labelled background. If I turn off page 1 the thumbnail disappears.

I thought the two images may be the result of my files being too large, they are 137MB, under preferences the max image size was set to 128MB, I upped this to 164MB but it has made no difference.
If I import the pages as images I get two images, one the full size image, the other a very small image, both identical.

2017-10-28 20:33:46 UTC (over 6 years ago)
postings
11

Gimp channel mixer

The problem is not the channel mixer, if I select background I can use the channel mixer OK, but the thumbnail is still in the image, my problem therefore is importing the image properly, why is the image being imported as two pages?

Thankyou for replying so quickly earlier, I did not expect to receive a reply on a Saturday evening, I have been looking at a computer for too long now, I'm going for a beer, will log on later.

2017-10-29 08:18:20 UTC (over 6 years ago)
postings
121

Gimp channel mixer

When I open (I don't see an Import option) a tiff file I don't get asked whether I want to open it as layers. This was a file that I exported as tiff from GIMP.

Which program was used to save the tiff file that you are opening? Could it have saved the thumbnail as a separate layer rather than as a thumbnail?

If so and this ends up as the active layer it would be the one that the channel mixer altered as noted in your first post. This would agree with you saying that the channel mixer will work on the background if you select it.

If the thumbnail is actually a different layer you could simply delete the layer.

(I have just checked that when I use Export As to save a jpg as a tiff the advanced option to save the thumbnail is selected but I don't see the same problem when I open the saved file with GIMP.)

The problem is not the channel mixer, if I select background I can use the channel mixer OK, but the thumbnail is still in the image, my problem therefore is importing the image properly, why is the image being imported as two pages?

Thankyou for replying so quickly earlier, I did not expect to receive a reply on a Saturday evening, I have been looking at a computer for too long now, I'm going for a beer, will log on later.

rich404
2017-10-29 08:25:25 UTC (over 6 years ago)

Gimp channel mixer

The problem is not the channel mixer, if I select background I can use the channel mixer OK, but the thumbnail is still in the image, my problem therefore is importing the image properly, why is the image being imported as two pages?

Thankyou for replying so quickly earlier, I did not expect to receive a reply on a Saturday evening, I have been looking at a computer for too long now, I'm going for a beer, will log on later.

Going for a beer sounds good to me.

There are image formats where the file contains both the image and a thumbnail used by some applications to show the image quickly usually for selection. That is what you have. Two solutions, trial and error to determine the full image or open both and delete the unwanted layer.

quote...I'm trying to use the GIMP channel mixer to reverse the red and green channels in a TIF image. I'm using GIMP 2.9.6

Might not be as simple as the channel mixer, One way is decompose the image to RGB layers.

Duplicate the decomposed image and copy/paste Red from no2 to Green in no1. Green from no 2 to Red in no1

Recompose the first decomposed image.

2017-10-29 08:46:40 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Going for a beer sounds good to me.

There are image formats where the file contains both the image and a thumbnail used by some applications to show the image quickly usually for selection. That is what you have. Two solutions, trial and error to determine the full image or open both and delete the unwanted layer.

quote...I'm trying to use the GIMP channel mixer to reverse the red and green channels in a TIF image. I'm using GIMP 2.9.6

Might not be as simple as the channel mixer, One way is decompose the image to RGB layers.

Duplicate the decomposed image and copy/paste Red from no2 to Green in no1. Green from no 2 to Red in no1

Recompose the first decomposed image.

2017-10-29 09:15:52 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Good morning all, The image I was working on was created by Nikon's ViewNX2 editor, the original image format was Nikon's raw image .NEF extension, I exported this as a TIFF and then imported it to GIMP.

In ViewNX2 the images are stored with a preview thumbnail, so I think you have hit the nail on the head, I got myself confused at first because I didn't notice the thumbnail in the image before I used the channel mixer. The image is an infrared photo, it's mostly sky and the thumbnail didn't stand enough for me to notice it. It's also so tiny that it can't be seen in the image layer page 1. After swapping The red and blue channels (not green, another mistake) the colours changed enough for the thumbnail to be obvious. I wrongly assumed that the channel mixer had created the thumbnail, in fact it was there all the time.

Now I understand the problem I think I'll be OK, for a while anyway.

I bought Klaus Goelker's book "GIMP 2.8 for photographers" last week, I'm working my way through it and thought I was doing OK, but I got myself too confused to sort this one.

Before installing GIMP I read a review which said that GIMP was a very good program, but the learning curve was steep. I think they were right on both points.

Thankyou for your assistance, I know what I'm going to be doing during the long winter nights.

2017-10-29 11:44:00 UTC (over 6 years ago)
postings
121

Gimp channel mixer

I've just tried converting a file from jpg to tiff with ViewNX V2.10.3.

When opening in GIMP I get an error message about a null byte in the date field but it then opens the file as two layers with the top (active) layer being the thumbnail exactly as you said. Looks like this is a bug in ViewNX2.

Exporting a file in GIMP with the thumbnail selected doesn't cause this problem.

At least you have a workaround.

Good morning all, The image I was working on was created by Nikon's ViewNX2 editor, the original image format was Nikon's raw image .NEF extension, I exported this as a TIFF and then imported it to GIMP.

In ViewNX2 the images are stored with a preview thumbnail, so I think you have hit the nail on the head, I got myself confused at first because I didn't notice the thumbnail in the image before I used the channel mixer. The image is an infrared photo, it's mostly sky and the thumbnail didn't stand enough for me to notice it. It's also so tiny that it can't be seen in the image layer page 1. After swapping The red and blue channels (not green, another mistake) the colours changed enough for the thumbnail to be obvious. I wrongly assumed that the channel mixer had created the thumbnail, in fact it was there all the time.

Now I understand the problem I think I'll be OK, for a while anyway.

I bought Klaus Goelker's book "GIMP 2.8 for photographers" last week, I'm working my way through it and thought I was doing OK, but I got myself too confused to sort this one.

Before installing GIMP I read a review which said that GIMP was a very good program, but the learning curve was steep. I think they were right on both points.

Thankyou for your assistance, I know what I'm going to be doing during the long winter nights.

Rick Kline
2017-10-30 01:07:01 UTC (over 6 years ago)

Gimp channel mixer

Where are the TIFF images stored? What platform are you working on?

Can you right-click on a TIFF image in the computer’s directory window and select “Open with…”? That’s how I open most images with GIMP. The import functions are handled by GIMP, and I tend to use the defaults. Haven’t noticed a thumbnail layer yet, but in time… ? Shrugs.

I use an iMac running OS X 10.12.6

Rick

* * ** *** ***** ******** ************* ********************* It’s better to wave at a stranger than to ignore a friend * * ** *** ***** ******** ************* *********************

On Oct 29, 2017, at 5:15 AM, Oxonian wrote:

Good morning all, The image I was working on was created by Nikon's ViewNX2 editor, the original image format was Nikon's raw image .NEF extension, I exported this as a TIFF and then imported it to GIMP.

In ViewNX2 the images are stored with a preview thumbnail, so I think you have hit the nail on the head, I got myself confused at first because I didn't notice the thumbnail in the image before I used the channel mixer. The image is an infrared photo, it's mostly sky and the thumbnail didn't stand enough for me to notice it. It's also so tiny that it can't be seen in the image layer page 1. After swapping The red and blue channels (not green, another mistake) the colours changed enough for the thumbnail to be obvious. I wrongly assumed that the channel mixer had created the thumbnail, in fact it was there all the time.

Now I understand the problem I think I'll be OK, for a while anyway.

I bought Klaus Goelker's book "GIMP 2.8 for photographers" last week, I'm working my way through it and thought I was doing OK, but I got myself too confused to sort this one.

Before installing GIMP I read a review which said that GIMP was a very good program, but the learning curve was steep. I think they were right on both points.

Thankyou for your assistance, I know what I'm going to be doing during the long winter nights.

--
Oxonian (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list

2017-10-30 09:20:29 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Where are the TIFF images stored? What platform are you working on?

Can you right-click on a TIFF image in the computer’s directory window and select “Open with…”? That’s how I open most images with GIMP. The import functions are handled by GIMP, and I tend to use the defaults. Haven’t noticed a thumbnail layer yet, but in time… ? Shrugs.

I use an iMac running OS X 10.12.6

Rick

* * ** *** ***** ******** ************* ********************* It’s better to wave at a stranger than to ignore a friend * * ** *** ***** ******** ************* *********************

2017-10-30 09:29:29 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Good morning, The platform I'm working on is Windows 10, when I export TIFF files from NX2, I simply put them in a folder on the hard drive under Pictures. I then use Windows file manager to organise them.

I've tried right clicking and using the "open with" option, but GIMP is not an available option. I have some files saved in the folder in .xcf format, if I right click on these, GIMP appears in the "open with" options.

rich404
2017-10-30 10:36:56 UTC (over 6 years ago)

Gimp channel mixer

Good morning, The platform I'm working on is Windows 10, when I export TIFF files from NX2, I simply put them in a folder on the hard drive under Pictures. I then use Windows file manager to organise them.

I've tried right clicking and using the "open with" option, but GIMP is not an available option. I have some files saved in the folder in .xcf format, if I right click on these, GIMP appears in the "open with" options.

To open a RAW file directly in Gimp 2.9.x you need a plugin.

The example using a sample NEF file is in my linux Gimp 2.9.7 using the nUFRaw plugin which I had to compile myself because of changes to the Gimp 2.9 package.

For Windows, AFAIK the Partha version of Gimp 2.9.6 comes with nUFRaw pre-installed. see www.partha.com

Otherwise the two applications that Gimp recognises by default and will use, are Rawtherapee and Darktable. Both are monsters that will take over your computer, but the place to ask question on this is not here, but https://discuss.pixls.us/

rich: www.gimp-forum.net

Elle Stone
2017-10-30 11:06:17 UTC (over 6 years ago)

Gimp channel mixer

On 10/30/2017 06:36 AM, rich404 wrote:

Otherwise the two applications that Gimp recognises by default and will use, are Rawtherapee and Darktable.

And PhotoFlow, and any other raw processor that chooses to provide a plug-in using the same sort of plug-in code that RawTherapee, darktable, and PhotoFlow provide.

Best,
Elle

rich404
2017-10-30 11:43:58 UTC (over 6 years ago)

Gimp channel mixer

And PhotoFlow, and any other raw processor that chooses to provide a plug-in using the same sort of plug-in code that RawTherapee, darktable,
and PhotoFlow provide.

Best,
Elle

Indeed there is PhotoFlow.

I do not normally reply to non-gimpusers-dot-com subscribers but...

The three mentioned have become applications that occasionally use Gimp rather than Gimp plugins. Wonderful.

Patrick Shanahan
2017-10-30 11:59:28 UTC (over 6 years ago)

Gimp channel mixer

* rich404 [10-30-17 07:48]:

And PhotoFlow, and any other raw processor that chooses to provide a plug-in using the same sort of plug-in code that RawTherapee, darktable,
and PhotoFlow provide.

Best,
Elle

Indeed there is PhotoFlow.

I do not normally reply to non-gimpusers-dot-com subscribers but...

a rather elitist attitude, isn't it?

does a "gimpusers" subscribee have *better* standing or knowledge or manners than "non-gimpusers-dot-com" scribers? and how would you know that someone using their own email addr was not a "subscriber" or maybe even a contributor/developer or someone who wanted to be?

but I may not qualify to even merit a reply :(.

(paka)Patrick Shanahan       Plainfield, Indiana, USA          @ptilopteri
http://en.opensuse.org    openSUSE Community Member    facebook/ptilopteri
Registered Linux User #207535                    @ http://linuxcounter.net
Photos: http://wahoo.no-ip.org/piwigo		    paka @ IRCnet freenode
rich404
2017-10-30 13:57:39 UTC (over 6 years ago)

Gimp channel mixer

* rich404 [10-30-17 07:48]:
a rather elitist attitude, isn't it?

does a "gimpusers" subscribee have *better* standing or knowledge or manners than "non-gimpusers-dot-com" scribers? and how would you know that someone using their own email addr was not a "subscriber" or maybe
even a contributor/developer or someone who wanted to be?

but I may not qualify to even merit a reply :(.

Not at all,and I have great respect for Elle Stone.

How do I know who-is-who

If you ever come come to gimpusers-dot-com you will see that forum members names are in blue, mailing list in grey.

Personally I hate mailing lists, stopped using the occasional academic list 20 years ago. The inability of subscribers to edit their posts continually amazes. Top posting 'thanks' followed by a page of nested quoted is not unusual.

When it comes to etiquette, probably got a better sense than many. At one time a four line signature was considered bad form.

Now to go and play at selecting pictures in the new CAPTCHA format that is a real PITA.

2017-10-30 16:36:54 UTC (over 6 years ago)
postings
11

Gimp channel mixer

Not at all,and I have great respect for Elle Stone.

How do I know who-is-who

If you ever come come to gimpusers-dot-com you will see that forum members names are in blue, mailing list in grey.

Personally I hate mailing lists, stopped using the occasional academic list 20 years ago. The inability of subscribers to edit their posts continually amazes. Top posting 'thanks' followed by a page of nested quoted is not unusual.

When it comes to etiquette, probably got a better sense than many. At one time a four line signature was considered bad form.

Now to go and play at selecting pictures in the new CAPTCHA format that is a real PITA.

There appears to be some confusion about raw loaders for GIMP 2.9.6. In response to rich404's post I tried opening a Nikon raw file directly into GIMP. It fails saying there is no raw loader installed, it then suggests using darktable or rawtherapee.

I looked at the PARTHA.com site and it does state that uFRAW is preinstalled on GIMP 2.9.6, this is not true in my case.

Another piece of confusion is on the sourceforge website where it states that Ufraw is only available as a standalone program under windows 10, it says there is a GIMP plug-in included, but it does not work.

rich404
2017-10-30 17:27:35 UTC (over 6 years ago)

Gimp channel mixer

There appears to be some confusion about raw loaders for GIMP 2.9.6. In response to rich404's post I tried opening a Nikon raw file directly into GIMP. It fails saying there is no raw loader installed, it then suggests using darktable or rawtherapee.

I looked at the PARTHA.com site and it does state that uFRAW is preinstalled on GIMP 2.9.6, this is not true in my case.

Another piece of confusion is on the sourceforge website where it states that Ufraw is only available as a standalone program under windows 10, it says there is a GIMP plug-in included, but it does not work.

You have every right to be confused.

The situation is:

ufraw is old and not updated - last release 2015. Apart from that, due to code changes (file-raw-placeholder) the plugin does not work with Gimp 2.9.6

An updated re-mix nufraw https://sourceforge.net/projects/nufraw/ is more recent but AFAIK there is no compiled-for-windows plugin there. This code also needs updating to work with Gimp 2.9.6

For Windows Gimp 2.9.6 from www.gimp.org it is a vanilla version with no'extras'

Partha's Windows Gimp 2.9.6 standard edition does include a working nufraw that will import a RAW image into Gimp from Gimp's open dialogue.

2017-10-30 17:38:36 UTC (over 6 years ago)
postings
11

Gimp channel mixer

You have every right to be confused.

The situation is:

ufraw is old and not updated - last release 2015. Apart from that, due to code changes (file-raw-placeholder) the plugin does not work with Gimp 2.9.6

An updated re-mix nufraw https://sourceforge.net/projects/nufraw/ is more recent but AFAIK there is no compiled-for-windows plugin there. This code also needs updating to work with Gimp 2.9.6

For Windows Gimp 2.9.6 from www.gimp.org it is a vanilla version with no'extras'

Partha's Windows Gimp 2.9.6 standard edition does include a working nufraw that will import a RAW image into Gimp from Gimp's open dialogue.

Thankyou for shedding some light on this, I think I will continue as I was, exporting a TIFF from NX2 and opening that in GIMP.

Now that the source of the rogue thumbnail has been found, it's a simple matter to just delete it's layer and carry on. It does not appear to cause any problems later.