Level: very entry level (If you know how open and save a file in gimp this is more than half of it.)
But simple tricks could be also useful for advanced users

First, please check if the final result could interest you. Here it is used on a portrait.

(image credit to http://mortemer.deviantart.com/gallery/, used with permission...her gallery is full of beautiful portraits )



...And this is the immediate result of the 3 click manipulation.



Here I used it on a schoolbus.



Same truck after 2 clicks.



Of course you can try this same manipulation on renders and more. This is an example:




It could work also for urban or natural landscapes.

If you're still interested we will go on with...

TECHNICAL LIMITATIONS

1) You can't scale the manipulated image up or down.
By scaling your image will be ruined by an optical interference called the "Moire' Effect".
http://en.wikipedia.org/wiki/Moir%C3%A9_pattern (more on http://www.illuweb.it/moiranim/moirmenu.htm)

This is a visual example:

ORIGINAL



IF SCALED



But don't worry, just you need to know that FIRST you must scale your image
...or use an image with the right size to avoid the problem

[NOTE]If you need to know how to scale images see NOTE at the end [/NOTE]

2) Take care to work with the zoom always set to 100%.



If not, you will not able to see the real effect (again for the moire effect:this time it will not ruin the manip but its preview).

Just 1% more or less can create moire interference.

-----


-----


PRACTICE

1 First Click
Once you open your image, go to the "image" menu and look for mode, then indexed

Below are shown the correct settings:



You can also try the other kind of dithering because they can give different, though not 100% predictable results. (except "none", that will create only an sort of ugly photocopy)
Usually I get the best result with the setting highlighted in the screenshot.

2 Second click

well now you need to click on "OKAY".

3 Third click

And of course, if you like, you must go to the file menu and save it
Since is a flat image you don't need to save as xcf...a good lossless format is.png ...for use on the web also jpg is fine

POSTWORK: Further editing

If you want to retouch this kind of manipulation you need to first convert in RGB (Image>Mode>Rgb)
Conversion will not reverse the effect (only undo can undo that change) but will make available all the tools and filters of Gimp's
that in ndexed mode will be mostly greyed out and inactive

LAST THING TO KNOW

With this trick you can get a very interesting result, but it didn't allow for regulation or fine-tuning, in the next part we will see how to overcome this limitation.

To multiply the chances of success a couple of additional clicks will be needed

APPENDIX

About the B&W photomontage (the truck with the “punisher” and a soldier)
I used the same routine for the 3 images.(Punisher and soldier were 2 renders )
Then I just did File>Open as Layer for the image of the schoolbus as well as the two render images, and then I moved them to the best position.

This requires a minimum of knowledge about the layers

If you don't know what the heck a layer is... please wait until the next part: a basic knowledge of layers will be a by-product
of our next manipulations in chapter 2 and 3

Not abstract knowledge...but something useful to achieve immediate results in no time

But don't overlook the links for theoretical deepenings ...to get more and more immediate results you must grab the basics
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NOTE: How to Scale images
To do it you ,once you open your image you look in the image window then go to the [image
[menu and then to scale imageand you will see something like this:



Then enter the width or the height you want. Just to the right of the input boxes where you entered your scale values, is a little icon that looks like chain links. Make sure the chain is "linked", if it isn't your image may distort when it is scale. If the icon is unlinked (the default is "linked"), then click it to lock the links together. Locking the links maintains the aspect ratio of the height and width of your image.

For best quality when scaling use CUBIC interpolation in the dropdown menu located in the same dialog. (Normally the default is set to LINEAR, change it. You can also permanently set this preference in the File>Preferences dialog in the main Toolbox window.)

PART 2

1- CONVERTING COLOR IMAGES TO B&W(GREYSCALE)- 2 -FROM GREYSCALE TO B&W ILLUSTRATIONS (1 BIT B&W) ...[b]Everything in ONLY 7 Clicks
[/b]
The purpose is multiply the chances of success of the 1bit B&W conversion as described in chapter 1

BUT there is a very interesting thing to notice

The intermediate step ,a 1 step conversion in greyscales of a colours photo, could of more general interest and more rewarding for a larger number of users then the whole process

So this “intermediate step” deserve its own chapter ,becouse even if is a 2 “click process” it is very basic and important .
imagines will explain better then words ,thank to Mortemer that left me use this pic from her beautiful Stock Gallery on Deviant Art http://mortemer-stock.deviantart.com

ORIGINAL



CONVERTING COLOR IMAGES TO B&W(GREYSCALE)- (that is just 1 click)


.

2 -FROM GREYSCALE TO B&W ILLUSTRATIONS (1 BIT B&W)

About comix style and illustration in another step ,by converting those grey scale images in 1 bit indexed we will ended with something alike this.




Thank to the script we can extract all the channel with 1 click
And thank to GAP we could export (save) all the 18 layers as single images in a single step
A quick work in few steps ...few but really important to grab the basic of image manipulation



GETTING READY

To get ready first we need to install

1) a script fu ,this http://sourceforge.net/projects/lasmz/just click on “download” to download.

If you don't know what is a script fu don't worry[/b], all you need to know now is that a script could make you spare a lot of time and that for useful theorical deepening you can visit http://docs.gimp.org/en/gimp-concepts-script-fu.html

[NOTE]If you need instruction to install script see NOTE 1 at the end of tut [/NOTE]


2 GAP, yes the Gimp Animation Package

Maybe you know that Gap is very complex and is mainly used for animations
Don’t worry …we will use it in very simple way and GAP is not useful only for animations even if that is the most obvious use
We will use it to save time and efforts
[NOTE]For how to install gap see:NOTE 2 at the end of the tut[/NOTE]

[NOTE] Instead then the script fu you can use the decompose plugin several times.
It’s a longer process but could be rewarding for learning purpose
If interested here you can find the how tohttp://www.gimp.org/tutorials/Color2BW/
[/NOTE]

------------------------------------------------------------------------PRATICE----------------------------------------------------------------------------
---------------------------------1- CONVERTING COLOR IMAGES TO B&W(GREYSCALE)- -------------------------------------------

Well ..if you didn’t open yet your image in Gimp, please do it now

CLICK 1

Image menu\script fu\lasm’s special FX\channel extract



Click on it

[NOTE]NOTE FOR [b]WINDOWS USERS
If the Script don't show up

For some Microsoft’s reason the script's interface could be displayed minimized at the very bottom of your screen , in the taskbar as in this screen shoot



If so ,just click on it to enlarge...and blame Microsoft not me for the extra click![/b][/NOTE]


CLICK 2

Let this default setting …and click okay



Next you will see something quite delusive and almost fully black
sample....Don’t worry that is only the top Layer (Layer http://docs.gimp.org/en/gimp-concepts-layers.html )

many of the other layer are much more interesting as self standing images.
(and to create mask or selections for further editing)

Browse those layer now is not strictly needed for our purpose but if you are curious to do it and you don’t know how to do you can read NOTE 3 "How to browse the layers" at the end of the tut

A by effect of this intermediate step is to make more clear concept as layers and channel

Is worth to know in this case that each layer correspond to a channel http://en.wikipedia.org/wiki/Channel
And that every channel look as a grey scale image (some quite weird ..but yet in grey scale)
So from this simple step we get as layers

1) The Red , Green , and Blue channels for the RGB colour space ( color space see here http://en.wikipedia.org/wiki/Color_space

Link image

2) The Luminosity, A, and B channels of the LAB color space

The luminosity channel is worth of a look…
But till we get also the A and B channel we could even spare a look also to them …just to see how it look like something as "A and B Channels of AB colour space”.

And with a simple editing sometimes even this 2 channel could be used to create self standing images, mask or useful selection


3) Hue,Saturation,and Value channels from HSV colour space
The Value channel look as a good negative ..(..,and the negative of something that look as negative should look as a good "positive"...

The Hue and Saturation channels usually are not very interesting as self standing images
But since we get them for free we can even see how they look like

4) Cyan,Magenta,Yellow,K(black) for CYMK colour space For some reason unknown to me with this plugin we get not not 4 but 7(?) channels for the CYMK color space

4 seem quite interesting
The other 3 could be useful as “negative”

More we have allways our original image that safely lie on the bottom as background


CLICK 3

Now you must save (we need to do now to go with next steps) WITHOUT CLOSING the image
Best way to save in Gimp a image with more layers is always as .xcf
Don’t click on nothing now!! …just press together “shift” “ctrl” and “s” key:
( by using hot key we do quicker)

You will see this …now click here on this microscopic triangle



Create a new folder YOU MUST DO IT! From here


CLICK 4
Final extension of your image must be .xcf.
now save …Click okay!

BUT DON’T CLOSE THE IMAGE!! YOU MUST ONLY SAVE

IT HAS TO BE OPEN FOR NEXT STEP

CLICK 5

Image menu\video\split image into frames ...click it!


CLICK 6

Now you want everything saved as .png

This because png is the best for quality even if highly compressed, and png images could be browsed with any viewer and they can even be used for the web

Check to have set the correct parameters


and click okay

CLICK 7
Well ,last one



You can compress a png as you want it will not loose quality so you can set compression to the max.
And then click okay.
All the layers are now exported as images and saved in the same folder where you save the multilayered .xcf

(They will be numbered in a weird way because in that way they could be used also as frames for animation by the GAP…

You can notice that same images (channels) look as negatives (they “look as”, they are neither positive or negative) …and that the negative of something that look as a negative will look as a positive ,often a quite interesting one


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---------------------------------2 FROM GREYSCALE TO B&W ILLUSTRATIONS (1 BIT B&W)--------------------------------------

Well for that after CLICK 3
1 image menu\ image\ duplicate
2 image menu \image\mode\indexed mode …choose 1 bit indexed Mode with dithering…exactly as explained in chapter 1 or in the summary on top.

Then you can save using : image menu\video\split images in frames as png ...But first you need to convert them back in RGB (Most of Gimp and Gap tool work only on RGB images)

This is a way to get "immediate results" in few click: by starting to grab the basic of image manipulation


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NOTE 1 installing a zipped script fu

Windows
to install it ,once downloaded (in a meaningful place as the desktop)you must unzip in
C:\Programmi\GIMP-2.0\share\gimp\2.0\scripts

Linux

If you are using Linux I bet you can figure out how to install a script or a plugin in Gimp
If no please have a look to the READ ME file included with the script

------------------------------------------------
NOTE 2: installing GAP

Windows

This is the link for the WINDOWS version
http://prdownloads.sourceforge.net/gimp-win/gimp-gap-2.2.0-setup.zip?download

chose the closest mirror and just download it
… unzip it on the desktop and click on the exe

AFTER INSTALL GAP...

...NO ANY NEW ICON WILL BE DESPLAYED ON THE DESKTOP ..no new voice will be listed in the start menu...but don’t worry GAP is installed ,is now inside Gimp .
Its menu is in the image menu ..here



OF course is displayed ONLY if a image is open

--------------------------------------------

NOTE 3 How to browse the layers

First we need to open a layer windows, this is my favourite way to do
Look the screenshoot , you can see a microscopic triangle.


Microscopic triangles often hide the most useful features ..by exploring it with the mouse as by magic a huge menu will pop out

That will add to your toolbox the layer windows highlighted in this other screenshoot

Now look the layer windows

Notice the “eye” icon:
If you uncheck the eye icon of the top layer.. the top layer will become invisible.
So you could see the one beneath…and so on
In this way you can browse all the layers

------------------------------- APPENDIX ---------------------------------------------------------------

OTHER WAYS TO CONVERT COLOUR IMAGES IN GREYSCALE

Well there are other 4 main ways to convert ,with different results a colour image in greyscale : .... 2 are quite interesting

1 Channel Mixer

Is in " image menu/Filter/Colors/Channel Mixer" or to say with images:




You saw how much could be different the grayscales of the same image as displayed from the 3 channels RED GREEN and BLUE.
The channel Mixer make you available all the possible “in between” results with a real time preview

More on channel mixer http://docs.gimp.org/en/plug-in-colors-channel-mixer.html



It will NOT mix other channels then the ones of the RGB colour space
More info http://docs.gimp.org/en/gimp-tool-hue-saturation.html

2 Saturation luminosity contrast

It is in " Image menu/Tools/Color Tools/Hue Saturation ..." or to say with images:



Is clear that by setting saturation to minimum you will remove the colour.



But the other 2 slide could allow you to fine tuning the output.

More on this tool http://docs.gimp.org/en/gimp-tool-hue-saturation.html


3 Grayscale image mode

Is in " Image menu/Image/Mode/Grayscale "or to say with images:



If you convert the image mode in Greyscale(image menu\mode\greyscale)…all colours will be removed…quick but not very rewarding: No preview ,no regulations, no fine tune are possible.
It’s no even possible to edit this kind of images if you don’t convert first the image mode back to RGB

More on greyscale image mode
http://docs.gimp.org/en/gimp-image-convert-grayscale.html
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Just a little bit more useful of the "greyscale convertion method" ( result are almost the same, only in this case the image mode will be not changed )could be " Desaturate" http://docs.gimp.org/en/gimp-layer-desaturate.html

_________________________________________________________________________________________________
_______________________________________________________________________________________________


For Bandwich reason PART 3 ( "Adding colours to your cartoonized pic" ) will be a selfstanding tutorial and it will be NOT added here.
there we will see how to use the colours of your original pic and the several layer blending modes to add colour to your "cartoonized images"

OF course i will offer again " immediate results in few clicks"

Coming Soon on this board

i want part two! :l: here's what i've done.

My results:

Before:



The above image is a Public Domain image from http://www.fromoldbooks.org

After:



Nice results. Thanks for sharing that fotocomics. :h:

Have you done part 2 yet? If so, where can I find it?

ADDED part 2 (as second message)

Sorry for delay (a HD crash deleted the original)

thanks for part two! :w:

I'm afraid that to make it readable from absolute newbie i make to dispersive .
Could you follow easy or you are disturbed or confused from too much un-needed info ? (as ..how install script, gap, browse layer and so on)

i can follow it pretty well. :h:

EDITED :to make more readable



I hope now even better :w:

: Nobody try ? :

A nice and extensive tutorial!
.
Griatch

:h:

Well...in my opinion it deserve a big BUMP!