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Spectral Image

#1 User is offline   wbool63 

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Posted 20 March 2010 - 07:24 PM

Spectral Image Tutorial

I don't normally write tutorials and this is quite a complex one. It was very difficult to keep a balance between necessary content and still keep the length down as much as possible. I hope I have achieved this to some extent

Also Thank You ImageShack for free hosting these images

Outcome
This tutorial is really only a workflow map of different processes. It assumes some degree of knowledge and understanding of Gimp. Basically the Spectral Image is made by using a few filters and merging the end products with a background. I'll explain in some detail parts of the processes, but there is simply too much for a detailed step by step description.
Also note that some of the illustrations are from different process streams as it is almost impossible to screen capture events before and after an event.

Prepare the Displacement Map
Find a nice silhouette portrait . I have used here an image from Storm's Stock Pack. and cut out the head silhouette.
Posted Image
The cutout is desaturated, mounted on a black background and the contrast is increased.. Use whatever means you know to do this or use my image. I copied the layer and used multiply mode at 70 % to increase the contrast. Alternatively, use the contrast filter (Color/Contrast).I have added a white column above the head where the vertical lines will show through for the hair waves.

111 Cutting out the silhouette selection 222 Using the quickmask to tidy up the selection and Clone a bit more hair, add to black background 333 Desaturate the selected silhouette, add it to a black background , duplicate and multiply to add contrast , add the white column for the hair. background
Posted Image Posted ImagePosted Image
Save the image as a layered XCF and as a flattened jpg. Name it something meaningful like Spectral_ImgBump.jpg or use My BumpMap

EDIT It is a good idea to gaussian blur (3 -5) your finished Black and White bump map. This will give a smoother displace map.

Prepare the Vertical Grid
Open a white 640 x 480 Image . Make a grid (Filters/Render/Pattern/Grid). Look at the insets to see my settings to make the grid. Use the Select by Color tool to select the whites between the black lines and use the Blend Tool to fill the whites with a gradient of your choice. I used a colourful one.
Of course you could individually colour the whites in the area of the silhouette if you prefer that instead of the gradient. After the colour fill, select none to get rid of the marching ants and save as a XCF and as a flattened jpg. I named mine MyGrid.jpg
Posted Image

This shows how to do the blend
Posted Image

The Thumbnail shows how to do the bucket fill
Posted Image
Click to enlarge the Bucket fill screenshot
Or use MyGrid

Prepare the spectral face
Using the colour grid and the bump map we use the Displace filter (Filters/Map/Displace)to make a distorted face in colored bars. Using a Layer Mask we only reveal the face and place it on a black background. We use the bump map as the Layer Mask in the grid reveal. There are probably other more elegant ways of using another image's selections, using channels and selections or buffers, (by all means use them if you are familiar with those processes) , but I find the easiest way is to simply copy (Ctl-c and Ctl-V on the selected white Layer Mask. One thing I do is turn off Auto Follow Active Image when cross referencing images in Layer Masks.
Posted Image
The display filter works with a “bump”map ( a black and white image). White to 128 value displace one way and black to 127 value displace the other way. A sudden shift between values have a greater displacement than a gradual shift in values. It is important that the displacement or bump map and the target image are of the exact same dimensions. In this application the vertical shift is set to 0 See the inset for filter settings. Make sure you have the Black and white Bump Map selected in the choices
Posted Image Click here to Enlarge
Adding the Layer Mask. Click on the “Add Layer Mask” button in the Layers, Channels,Paths Dialog on the target (displaced vertical bars, with the face in it).
Posted Image Click Here to Enlarge
Once you have opened the Layer Mask by making it active (click on Show Layer Mask) it will have a Green border. Now switch the target image to the Bump Map and Select All (Ctl-A) Select to Clipboard (Ctl-C) and paste into the previous target image (the layer Mask )
Posted ImageClick here to Enlarge
111 and 222and 333 As you paste the bumpmap you create another layer which is discarded by highlighting the layer and clicking the trashcan.This gives you the Layer Mask with one layer. 444Now create a layer of black underneath
Posted Image Posted Image Posted Image Posted Image

111Click here to Enlarge 222Clickhere to Enlarge 333Click Here to enlarge 444Click Here to Enlarge

Altering the Hair, Using the IWarp Filter
The next image shows my settings for the IWarp filter. I Used a small arc motion to slowly draw out the hair. The comb is cleaned up with a circular painting of black. At this stage You could paint between the lines or really do whatever you like with the final face. You could use a graduated layer mask to "fade" the hair, as long as you end up with a single layer at the end. Don't take any notice of the titles as these were done to illustrate and do not necessarily follow order.
Posted Image

Using the Newsprint Filter and Grid Filter
In the original artwork there were some fine lines that showed through at the edge of the face and hair.
This can be done using the Newsprint filter (Filters\ Distorts\Newsprint). Posted Image
If you wish you can first select an area around the face and hair. I did not. Alternatively you can use the Grid filter and use a shaped dimpled gradient blend, white centered layer mask in a selection. See the following sequence.
Posted Image Posted Image Posted Image Posted Image
111Enlarge222 Enlarge333 Enlarge444Enlarge
I chose the simple method for this tutorial.

Final Assembly
I used another one of Storm's Stock Pack ( a Hubble Space Image ) as a background. I had to scale it and used the colors/curve tool to give it a bit more red. That is just my personal choice. You of course can do anything you like or choose any other background
Posted Image Hubble Image
The final assembly is made up of the Starscape background, which I duplicated and used two simple layer masks to stop the top of the starscapes to show through. The first layer on top of that is the face with the tiny lines and then two more faces without the lines. I have used some simple settings to show the outcome . Of course you are can do lots more if you wish.
Posted Image

And the final outcome

Posted Image

Edit a spelling mistake
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#2 User is offline   saulgoode 

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Posted 20 March 2010 - 07:24 PM

This is the best GIMP tutorial I've ever seen. Very well done!
Everybody makes their own fun. If you don't make it yourself it's not fun, it's entertainment.
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#3 User is offline   wbool63 

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Posted 20 March 2010 - 07:24 PM

saulgoode said:

This is the best GIMP tutorial I've ever seen. Very well done!

Saulgoode, Thank You very much
Wbool63
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#4 User is offline   2-ton 

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Posted 20 March 2010 - 07:24 PM

Whoa, looks challenging, but awesome!

*just checking to see if I can edit...the forum won't let me post a reply or quote right now!
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#5 User is offline   PhotoComix 

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Posted 20 March 2010 - 07:24 PM

you explained very well all the process :!:
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#6 User is offline   fencepost 

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Posted 20 March 2010 - 07:24 PM

Fabulous! I shall give this a try and post my results.
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#7 User is offline   fiery 

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Posted 20 March 2010 - 07:24 PM

Nicely done, thank you!
Posted Image
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#8 User is offline   2-ton's_alias 

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Posted 16 March 2010 - 01:57 AM

Lol, had to "ghost register" in order to be allowed to post!

I have gotten stuck with this tut. I have the black and white for the bump map, and I have the rainbow grid. What I can't get right is the displaced rainbow. Could you post a screen shot of the layers before and after, and maybe also the steps in order? I don't have enough experience with gimp to figure it on by myself.
Thanks,
two ton

*oh, my, now looks what has happened...my post got stuck up on top where no one will see it!
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#9 User is offline   Wbools_GhostWriter 

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Posted 16 March 2010 - 12:09 PM

2-ton's_alias said:

Lol, had to "ghost register" in order to be allowed to post!

I have gotten stuck with this tut. I have the black and white for the bump map, and I have the rainbow grid. What I can't get right is the displaced rainbow. Could you post a screen shot of the layers before and after, and maybe also the steps in order? I don't have enough experience with gimp to figure it on by myself.
Thanks,
two ton

*oh, my, now looks what has happened...my post got stuck up on top where no one will see it!


Hi 2T as you can see it is my Ghost answering. I hope I have answered your query.
If not, message me at Wbools_GhostWriter because I cannot post from wbool63.

Posted Image

I forgot to mention that the bumpmap AND the target image (rainbow bars) must be open (as Gimp images)on the desktop.
Thanks to ImageShack for Free Hosting.
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#10 User is offline   2-ton's_alias 

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Posted 16 March 2010 - 08:06 PM

Well, here is what happens with my trials. I open gimp, then I open both files...rainbow grid.xcf and black and white pic.xcf (also tried the jpg version). Then I go to the rainbow grid pic, filter>map>displace. The only choice I have is the rainbow grid pic...no dropdown list is showing even when I click the arrow, the black and white picture is not given as a choice. What file extension do both files need to be in. If I understand it, they are not layers in the same file, but separately opened files. IIRC, the first time I tried this, the y did give me both pics as choices but I don't remember how or why.
*as you can see I did finally redo it enough times to get the displace filter to give me the bump map choice. But...it's not displacing it's only moving the colors around...none of the lines are actually warping around the black and white differences. I even made it totally black and white for full contrast as in the screenie and changed the x and y numbers up and down...still no joy. Any ideas?
Posted Image
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#11 User is offline   Wbools_GhostWriter 

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Posted 17 March 2010 - 06:54 AM

2-ton's_alias said:

Well, here is what happens with my trials. I open gimp, then I open both files...rainbow grid.xcf and black and white pic.xcf (also tried the jpg version). Then I go to the rainbow grid pic, filter>map>displace. The only choice I have is the rainbow grid pic...no dropdown list is showing even when I click the arrow, the black and white picture is not given as a choice. What file extension do both files need to be in. If I understand it, they are not layers in the same file, but separately opened files. IIRC, the first time I tried this, the y did give me both pics as choices but I don't remember how or why.
*as you can see I did finally redo it enough times to get the displace filter to give me the bump map choice. But...it's not displacing it's only moving the colors around...none of the lines are actually warping around the black and white differences. I even made it totally black and white for full contrast as in the screenie and changed the x and y numbers up and down...still no joy. Any ideas?
Posted Image

Lookin at your picture ,it appears that that the filter is doing exactly what it is supposed to do. Black and white images (two tone as opposed to grey scaled) give very stark displacements. I show this to illustrate
Showing the difference
You can see the difference between the very sharp and gradual transitions.
I think you have been caught in what I believe is a bug in Gimp. If through some small error an image is scaled by a few pixels and saved it will not be reflected in the title of the document. So an image title that says 640x480 may not be 640x480 pixels.You can show this easily. Create an image (say 200x200) scale tool to 199x200 and save it. Magnify the image at 800 times and you can see the missing pixels at the edges. The title when you recall that file will still say 200x200. When you try to use that file as a bumpmap for a 200x200 image , it will not show up in the bumpmap choice. Now scale that map to 200 x 200 (even though it says 200x200) and it will work again. I believe that one of your images was not the correct size.
If you still have problems message me. I hope this helps
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#12 User is offline   2-ton's_alias 

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Posted 17 March 2010 - 02:07 PM

Hmmm, I had the same displacement problem when I had the bump image in greyscale. I guess it will take some trial and error to get the darks and lights properly set up. When I used greyscale, the displacement showed little wiggles on some of the skin, but not noticeably larger wiggles on the main features.
At least I did finally get the sizes to work together after fussing with it, so at least I have that much accomplished. Now to work on the displacement stuff...

OK, I got it, but it's ugly. I can't really get a nice displace effect that works with all the features. It's ok, but it's really hard to find the right combo of contrast in the eyes and mouth, without having too much detail in the rest of the face. I think one of my big problems is that I need to use a higher resolution picture to start off with. I'm going to have to take a lot of time to play with this.
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#13 User is offline   2-ton's_alias 

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Posted 18 March 2010 - 04:54 PM

OK, after some hand holding by Wbool, here is my latest effort. Better, but not quite as good as I'd like...it's all about lighting and sharpness of pic!
Posted Image
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#14 User is offline   mollie 

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Posted 18 March 2010 - 05:06 PM

2-ton's_alias said:

OK, after some hand holding by Wbool, here is my latest effort. Better, but not quite as good as I'd like...it's all about lighting and sharpness of pic!
Posted Image


wow that is excellent 2-ton. very good.... woo hoo......
alias - molly
Posted Image
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#15 User is offline   2-ton's_alias 

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Posted 19 March 2010 - 01:31 AM

I tried an experiment..I iwarped the rainbow grid a bit before I displace mapped it...to give it more interest and without getting a bunch of little curlie-q lines where there are pixilations and stuff. I also went crazy with the rainbow cloud...just to play around with iwarp and see what different settings would do. I think it would have looked better if I had made the whole back of the head go black ... like merge into the background. I forgot to add something into my background, lol, it's just plain black.
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#16 User is offline   Wbools_GhostWriter 

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Posted 19 March 2010 - 06:03 AM

2-ton's_alias said:

I tried an experiment..I iwarped the rainbow grid a bit before I displace mapped it...to give it more interest and without getting a bunch of little curlie-q lines where there are pixilations and stuff. I also went crazy with the rainbow cloud...just to play around with iwarp and see what different settings would do. I think it would have looked better if I had made the whole back of the head go black ... like merge into the background. I forgot to add something into my background, lol, it's just plain black.


2-T Playing around with the Iwarp That is a great idea!! You can easily merge the back of the head into the black. Copy the layer,(100% normal mode) give the layer a complete white layer mask.
Make the layer mask active and paint on it with a black airbrush at 30% where you want the head to disappear. That way if you botch it you still have the undisturbed layer underneath.

Cheers Wbools Ghost
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#17 User is offline   2-ton's_alias 

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Posted 19 March 2010 - 03:27 PM

woo...worked a charm. I did have to sneak in another background layer underneath the masked layer...but you can really mess around with the look of it. You can do more iwarping and mask painting to make it trail off into the distance, lol. Now I'm waiting for a requested pic to be sent to make the project I envision.
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#18 User is offline   2-ton 

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Posted 25 March 2010 - 07:34 PM

Finally got to this project. It's not bad, but I wasn't sure of all the steps for warping and adding the starscape properly. Anyway, here is my effort...if anyone has tips on how to make it better, I'm all ears.
Posted Image
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#19 User is offline   molly 

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Posted 25 March 2010 - 09:14 PM

Beautiful 2-ton. I wouldn't change any of it.......
Posted Image
Posted Image Click Me!
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#20 User is offline   wbool63 

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Posted 25 March 2010 - 09:34 PM

Great Result 2-T, I bet you are pleased with yourself. It is a reasonably difficult project. Well done!
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