Commit 57cb76cf authored by Pat David's avatar Pat David

Add tutorials from Ofnuts + update tutorials index

Add new tutorials:
* CircleImage
* GIMPProfile
* ImageFormats

These are all from Ofnuts to test formatting.
parent 7c68a49a
Title: Making a Circle-Shaped Image
Date: 2016-09
Modified: 2016-09-04T20:54:21-05:00
Author: Ofnuts
Template: page_author
Making a circle-shaped image
============================
**Foreword:** There are no circular images. There are only rectangular images.
But there can be images where corners are transparent, so that only a circle shows.
* First, make sure that your layer has an "alpha channel" (*Layer>Transparency>Add alpha channel*)(if it's grayed out, it means you already have one)
* Create a circular selection with the "Ellipse select tool (the 2nd one in the toolbox).
Use the "Tool options" dialog (*Windows>Dockable dialogs>Tool options* (top of list)).
* If you want a true circle, use the *Fixed* option: select *Aspect ratio* and enter `1:1`.
* Depending on what kind of marks you have, you can use:
* The diagonal framing (default): click on one corner, drag across a full diagonal and release at the opposite corner,
* The radial framing (check *Expand from center* in the Tool options): click on the center, drag across a half diagonal release on a corner.
* If the selection isn't perfect on the first try, you can move it (click around the middle) or extend it (click inside, near a border or a corner).
* Once you have the required selection, invert the selection (*Select>Invert*, or Ctrl-I) so that everything is selected, except your circle
* Erase the selection (*Edit>Clear* or [Delete] key). You should have your central circle left, surrounded by a checkerboard pattern
(this checkerboard is not part of the image, it just indicates the transparent parts of the image).
* You can reduce the checkerboard to the minimum by auto-cropping the image (*Image>Autocrop image*)
* Last, save the image in a format that supports transparency, like PNG (JPEG doesn't support transparent images...)
* If you are going to work further on the picture, save ist as XCF (Gimp native format).
<small>
<a href='http://creativecommons.org/licenses/by-sa/3.0/deed.en_US'>
<img class='cc-badge' src='http://i.creativecommons.org/l/by-sa/3.0/80x15.png' alt='Creative Commons By Share Alike'/>
</a>
<br/>
<span xmlns:dct="http://purl.org/dc/terms/">GIMP Tutorial - Making a Circle-Shaped Image</span> by Ofnuts is licensed under a [Creative Commons Attribution-ShareAlike 3.0 Unported License](http://creativecommons.org/licenses/by-sa/3.0/deed.en_US).</small>
Title: Your GIMP Profile and You
Date: 2016
Modified: 2016-09-04T20:54:21-05:00
Author: Ofnuts
Template: page_author
What is my "Gimp profile" and where do I find it?
=================================================
The "Gimp profile" is a directory/folder (actually a directory tree) where Gimp keeps information that pertains to you, the user:
* your windows and dialogs setup
* your settings and presets for some tools
* your keyboard shortcuts
* your brushes, gradients, palettes, patterns, fonts, scripts, plugins and brush dynamics (as opposed to those installed for the benefits of all users).
## Locating the Gimp profile
Since it is a personal folder, Gimp keeps it with others files that also belong to you, usually:
* In Windows XP: `C:\Documents and Settings\{your_id}\.gimp-2.8` (ie, a "sibling" of "Application Data" and "My Documents")
* In Vista, Windows 7 and later versions: `C:\Users\{your_id}\.gimp-2.8` (ie, a "sibling" of "Application Data" and "My Documents")
* In Linux: `/home/{your_id}/.gimp-2.8` (a.k.a. `~/.gimp-2.8`)
* In OSX: `/Users/{your_id}/Library/GIMP/2.8/` or possibly `/Users/{your_id}/Library/Application Support/GIMP/2.8/` (this could depend on the Gimp build you use).
The `.gimp-2.8` part is of course version-dependent, so in the near future you may have to look for `.gimp-2.9` (or you may still be using `.gimp-2.6`).
If you run several versions in parallel, you will have a profile for each, i.e., distinct profiles for Gimp 2.6 and Gimp 2.8, while all the successive updates to Gimp 2.8 will use the same profile.
### If you don't find it in the locations above
* If you are on Linux or OSX, keep in mind that the leading dot in the name makes many tools "omit" to display it,
so you may have to explicitly ask your file explorer to display hidden files to navigate to it.
* On all systems (and especially Windows versions), it can be elsewhere for several reasons,
for instance because the user profile has been moved to another partition/drive (especially with "roaming" users).
Here are two tricks to find it (they both assume that Gimp can run):
#### Trick #1
* *Edit>Preferences* and open the *Folders* tree in the left pane of the dialog.
* If you click on any of the folders (for instance, Brushes), the right pane will normally display two folders:
* The non-writable one is the one that holds system-wide features (brushes in this case), located somewhere in the Gimp installation tree
* The writable one is your own brushes folder in your Gimp profile: the Gimp profile is its parent folder.
#### Trick #2
* Open Filters/Python-fu/Console
* Enter this: `print gimp.directory` and srtoke [Enter]
## When to use the Gimp profile
Your Gimp profile is the right place to install additional material (scripts, plugins, brushes, palettes, fonts, gradients...).
It is a much better place than the system Gimp installation folder:
* Installing things there will not require admin privileges
* The additional items will not be wiped out by a Gimp re-installation
* They are more likely to be backed up since they are part of the user's data
## Repairing the Gimp profile
Gimp Startup failures can be caused by profile problems. In that case it is pointless to re-install Gimp,
since the re-installed version will re-use the existing profile and therefore fail in the same way.
It is usually much more efficient to just rename the profile (to `.gimp-2.8.disabled`, for instance) and restart Gimp.
Gimp will recreate a new profile directory on startup, which should fix any problems.
You can then copy your add-ons subdirectories to the new profile, checking periodically that Gimp will still start
with that modified profile.
<small>
<a href='http://creativecommons.org/licenses/by-sa/3.0/deed.en_US'>
<img class='cc-badge' src='http://i.creativecommons.org/l/by-sa/3.0/80x15.png' alt='Creative Commons By Share Alike'/>
</a>
<br/>
<span xmlns:dct="http://purl.org/dc/terms/">GIMP Tutorial - Your GIMP Profile and You</span> by Ofnuts is licensed under a [Creative Commons Attribution-ShareAlike 3.0 Unported License](http://creativecommons.org/licenses/by-sa/3.0/deed.en_US).</small>
Title: Image Formats Overview
Date: 2016-09
Modified: 2016-09-04T21:58:31-05:00
Author: Ofnuts
Template: page_author
Pros and cons of various images formats from a Gimp perspective
===============================================================
XCF
---
### Pros
* Native Gimp image format. Everything is saved: layers, selections, channels, paths
### Cons
* Not a "display" format, even if you can find codecs to display thumbnails of XCF image in file explorers.
* Bulky
* Color channels are coded on 8 bits (in Gimp 2.8)
### Recommended uses
* Saving all Gimp work
JPG
---
### Pros
* Compresses the files quite efficiently.
* Universally supported for display
### Cons
* Compression is "lossy" and it slightly alters the image data. In case of global changes (color, contrast...) repeated file editing will slowly degrade the image quality.
* At good quality levels, compression is invisible in photography, but can be seen (so called "artifacts") in computer-generated graphics and text.
* Doesn't support transparency
* Color channels are coded on 8 bits
### Recommended uses
* Display of photography
* Storage of photography
[A more complete FAQ on the subject](http://www.faqs.org/faqs/jpeg-faq/part1/)
PNG
---
### Pros
* Lossless format, all pixels are kept
* Supports partial transparency
* Produces small files with most computer graphics
* Supported by all browsers
### Cons
* Complex images (photos) are bulky
* Color channels are coded on 8 bits
### Recommended uses
* Web page widgets: banners, buttons, frames,...
* Computer graphics
* Screenshots (unless this screenshot contain mostly a photo)
GIF
---
### Pros
* Universally supported for animation
### Cons
* Only 256 colors per image, leads to blocky look
(a modern variant supports 256 colors per frame, but Gimp doesn't use it)
* Supports transparency but only as fully transparent/fully opaque
### Recommended uses
* Small animated images (in all other still-image uses PNG is a better alternative,
and for bigger animation modern HTML supports video)
TIFF
----
### Pros
* Lossless format, all pixels are kept
* Color channels can be coded in 16 bits
* Can store several images (layers)
* Supported by all image processing software.
### Cons
* Can be bulky on complex images
### Recommended uses
* Storage and exchange of high quality images
Raw images formats (NEF (Nikon), CR2 (Canon)...)
------------------------------------------------
### Pros
* No loss of information from the camera sensor (in theory)
* High-depth color channels (12 or 14-bit)
### Cons
* Proprietary (except DNG)
* Content format can change without notice (new camera models), this can impact support by your favorite software.
* Bulky
* Not suitable for display
### Recommended uses
* Storage of camera output, but a secondary copy in some universal format could be a good idea.
There are of course many other image formats, but the formats above cover most uses.
Use them unless you know better, they can usually be converted easily to any other format should the need arise.
<small>
<a href='http://creativecommons.org/licenses/by-sa/3.0/deed.en_US'>
<img class='cc-badge' src='http://i.creativecommons.org/l/by-sa/3.0/80x15.png' alt='Creative Commons By Share Alike'/>
</a>
<br/>
<span xmlns:dct="http://purl.org/dc/terms/">GIMP Tutorial - Image Formats Overview</span> by Ofnuts is licensed under a [Creative Commons Attribution-ShareAlike 3.0 Unported License](http://creativecommons.org/licenses/by-sa/3.0/deed.en_US).</small>
......@@ -13,12 +13,29 @@ Use GIMP for simple graphics needs without having to learn advanced image manipu
[Simple Floating Logo][]
This tutorial walks through some basic image and layer manipulation techniques.
[Making a Circle-Shaped Image][]
[Layer Masks][]
An introduction to using layer masks to modify the opacity of a layer.
[Basic Color Curves][]
A first look at the Curves tool and adjusting color tones in an image.
[Your GIMP Profile (and You)][]
What the GIMP Profile is and how to use it.
[Image Formats Overview][]
[GIMP Quickies]: {filename}GIMP_Quickies/index.md
[Simple Floating Logo]: {filename}Floating_Logo/index.md
[Layer Masks]: {filename}Layer_Masks/index.md
[Basic Color Curves]: {filename}Basic_Color_Curves/index.md
[Your GIMP Profile (and You)]: {filename}GIMPProfile/index.md
[Making a Circle-Shaped Image]: {filename}CircleImage/index.md
[Image Formats Overview]: {filename}ImageFormats/index.md
## Photo Editing
......@@ -32,6 +49,11 @@ Using multiple layer masks to isolate specific tones in your image for editing.
Using high bit depth GIMP's 'Colors/Exposure' operation to add exposure compensation to shadows
and midtones while retaining highlight details.
[Digital B&W Conversion]: {filename}Digital_Black_and_White_Conversion/index.md
[Luminosity Masks]: {filename}Luminosity_Masks/index.md
[Tone Mapping with 'Colors/Exposure']: {filename}Tone_Mapping_Using_GIMP_Levels/index.md
## Programming
......@@ -57,10 +79,5 @@ Bear in mind that this list is being provided for legacy reasons only.
[Basic GIMP Perl]: {filename}Basic_Perl/index.md
[Automate Editing]: {filename}Automate_Editing_in_GIMP/index.md
[Automatic Creation of XCF from JPG]: {filename}AutomatedJpgToXcf/index.md
[Basic Color Curves]: {filename}Basic_Color_Curves/index.md
[Digital B&W Conversion]: {filename}Digital_Black_and_White_Conversion/index.md
[GIMP Quickies]: {filename}GIMP_Quickies/index.md
[Layer Masks]: {filename}Layer_Masks/index.md
[Luminosity Masks]: {filename}Luminosity_Masks/index.md
[Simple Floating Logo]: {filename}Floating_Logo/index.md
[Tone Mapping with 'Colors/Exposure']: {filename}Tone_Mapping_Using_GIMP_Levels/index.md
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