Types of photo editing
Corrective editing
Your lens is inducing chromatic aberrations such as purplish halos ? You can correct this easily in post-processing.
Colors are missing on a damaged print or your old film photograph ? Colorizing techniques are available.
Your lens is a wide angle and it is slightly distorting the image ? Darktable has lens profiles embedded to help you achieve a more accurate result.
Or maybe you want to crop into the image, to fix the perspective angle a little bit to make the frame better ? Dedicated tools can help you with that.
RAW photography
If you own a reflex or if you have an advanced software on your smartphone, you may be able to record your photos in a file format named RAW (depending on the manufacturer, the file extension will be different (2.1)).
A raw image file contains all relevant information from your camera sensor at the moment the image was taken, these are just plain data.
Although some advanced image viewers allow you to view these types of file, a raw image file is not designed to be viewable by itself and needs calibration before it should be shared with the world.
Once again, one photograph is a very subjective representation of what was to be seen at the moment it was taken: in fact, as soon as a photo is converted from raw to jpeg or png file format, a range of post-processing settings are already applied by your camera !
Indeed, most advanced cameras (such as mirrorless and reflex) have in camera settings to adjust color saturation, brightness, and even details.
A raw photo file is bigger, has more information and settings that you can change afterwards, while a jpeg is a reduced, compressed version of the original data. The color temperature for instance can be changed on a raw file afterwards, without losing quality.
When to use RAW ?
Raw files are also very useful under low light conditions as they are holding much more details hidden in high lights and shadows.
Nowadays technology has grown far and even on a compressed JPEG you can apply a wide range of optimisations / alterations.
Of course if your intent is to do a large print with the photograph, it will be always advised and better to shoot in RAW. But for general purposes, jpeg is fine
Creative / Fun
Create your own filters and styles
With time and practice you will be defining your own editing style and workflow. No need to use pre-made filters ! You can do better and have fun tweaking your own styles.
Matte painting
Matte painting is a set of photo editing and painting techniques which have been used since movies are made, to make creative, fictional or historical backgrounds come to life. This is also a process used to make artistic scenery.
While matte painting is subject on its own, it won’t be detailed in this ebook. Many other resources about it are available online and you can look it up as a source of inspiration.
Technical alterations
Technical information is related to the nature of the file you are working with.
The most common optimization which is overlooked by beginners is file size and compression. Also you may want to crop an image while keeping a specific aspect ratio (or format) for the image, such as in portrait mode to share it on smartphone social networks.
One other common case you could face is about converting a file format to one another, for instance you could transform a jpeg to a png (standard for transparency) or vice versa.
Other use cases explained in this book regarding technical alterations are about creating a panoramic landscape, changing the color space and altering data embed in the image (exif).