add some info about RS03 in readme

README.md

@@ -44,37 +44,57 @@ with this version 10+ years from now. Regression tests are here to ensure this i
 
 For a more detailed explanation of the algorithms, please refer to the [codecs specification PDF](documentation/codecs.pdf).
 
-:one: **RS01** creates error correction files which are stored separately from the image they belong to.
+:arrow_forward: **RS01** creates error correction files which are stored separately from the image they belong to.
 The artefact is an **ecc** file, which must be stored on another media than the one we're protecting.
 
-:two: **RS02** creates error correction data which is added to the medium to protect, we call this *augmenting* the image we're protecting.
+:arrow_forward: **RS02** creates error correction data which is added to the medium to protect, we call this *augmenting* the image we're protecting.
 Damaged sectors in the error correction information reduce the data recovering capacity,
 but do not make recovery impossible - a second medium for keeping or protecting the error correction information is not required.
+Intelligent adaptive reading is also available when reading a damaged RS02-protected disc: dvdisaster will only attempt
+to read the minimum amount of required sectors to be able to rebuild the image, using a so-called "divide and conquer"
+seeking mechanism, cutting off up to 90% of the time required to read and recover a damaged media.
 
-:three: **RS03** is a further development of RS01 and RS02. It can create both error correction files and
+:arrow_forward: **RS03** is a further development of RS01 and RS02. It can create both error correction files and
 augmented images, with the following added features:
 
-- RS03 can use multiple CPU cores and is therefore **much** faster than RS01/RS02 on modern hardware.
-- RS03 error correction files are - contrary to RS01, and to a lesser extent RS02 - robust against damage.
-- RS03 is more robust, but also more restrictive: The augmented image must completely fill the medium now while the size of augmented images can be freely chosen in RS02.
- The changes for parallel computation and higher robustness make RS03 a bit less space efficient,
- e.g. RS03 error correction data has slighly less (around -3%) error correction capacity than its RS01/RS02 counterparts on images with equal size.
+- It can use multiple CPU cores and is therefore **WAY** faster than RS01/RS02 on modern hardware.
+- RS03 augmented images and error correction files are - contrary to RS01, and to a lesser extent RS02 - robust against
+ damage of the dvdisaster-added recovery data itself
+
+There are, however, a few cons that must be noted:
+
+- In image mode, the RS03 augmented image file size will be picked up from a predefined list of well-known medium sizes,
+ while the size of augmented images can be freely chosen in RS02. This is the "price to pay" for the added robustness
+ of the correction data.
+- In image mode, intelligent adaptive reading is not available for RS03-protected images. The "divide and conquer"
+ algorithm will still be used, but dvdisaster will not stop as soon as enough sectors have been recovered to rebuild
+ the image: it'll attempt to read them all until you stop it, or until it tried to read all the sectors. You can still
+ stop it manually and attempt a "verify" of the resulting image file, to see if enough data has been read for recovery,
+ otherwise resuming the adaptive reading until this is the case.
+- The changes for parallel computation and higher robustness make RS03 a tiny bit less space efficient, e.g. RS03 error
+ correction data has slighly less (around -3%) error correction capacity than its RS01/RS02 counterparts on images with
+ equal size. This is usually considered a cheap price to pay for the added robustness against corruption.
 
 Rough comparison table:
 
-| Codecs | RS01 | RS02 | RS03 |
-|------------------|--------------------------------|--------------------------------|--------------------------------|
-| Robustness\* | :star: | :star::star::star: | :star::star::star::star::star: |
-| Speed | :star::star: | :star: | :star::star::star::star::star: |
-| Space efficiency | :star::star::star::star::star: | :star::star::star::star::star: | :star::star::star::star: |
-| Augmented images | :x: | :heavy_check_mark: | :heavy_check_mark: |
-| Separate files | :heavy_check_mark: | :x: | :heavy_check_mark: |
+| Codecs | RS01 | RS02 | RS03 |
+|--------------------------------------|--------------------------------|--------------------------------|--------------------------------|
+| Create ECC-augmented images | :x: | :heavy_check_mark: | :heavy_check_mark: |
+| Create separate ECC files | :heavy_check_mark: | :x: | :heavy_check_mark: |
+| Robustness :one: | :star: | :star::star::star: | :star::star::star::star::star: |
+| Space efficiency | :star::star::star::star::star: | :star::star::star::star::star: | :star::star::star::star: |
+| Computational generation speed :two: | :star::star: | :star: | :star::star::star::star::star: |
+| Computational repair speed :two: | :star::star::star: | :star::star::star: | :star::star::star: |
+| Damaged media recovery speed :three: | :four: | :star::star::star: | :star: |
+| Supports custom augmented image size | :four: | :heavy_check_mark: | :x: |
+
+:one: Robustness against corruption of the dvdisaster-added ECC parts themselves. The higher the ranking, the less it is likely than a few badly located damaged sectors render the whole correction impossible because they affect dvdisaster metadata on-disc. For example corruption of the first dozens of sectors of an image can make RS02 entirely unusable regardless of the redundancy.
 
-\*Robustness against corruption of the dvdisaster-added ECC parts themselves
+:two: When algorithm is CPU-bound, i.e. generating or repairing an image stored on a SSD/NVMe drive.
 
-A rough decision chart follows:
+:three: Using adaptive reading when supported (RS02), linear reading otherwise (RS03), assuming a badly damaged media, taking into account the time the drive takes to try to read damaged sectors.
 
-![dvdisaster codec decision chart](https://i.imgur.com/QTgiack.png)
+:four: Only applicable to augmented images.
 
 # :bulb: Rationale