replaced images; added alt-text

windows/deployment/update/PSFxWhitepaper.md

@@ -8,7 +8,7 @@ ms.sitesec: library
 author: Jaimeo
 ms.localizationpriority: medium
 ms.author: jaimeo
-ms.date: 10/17/2018
+ms.date: 10/18/2018
 ---
 
 # Windows Updates using forward and reverse differentials
@@ -47,19 +47,19 @@ updates optimized for any origin/destination revision pair. It does this by
 calculating forward the differential of a changed file from the base version and
 its reverse differential back to the base version. Both forward and reverse
 differentials are then packaged as an update and distributed to the endpoints
-running the software to be updated.
+running the software to be updated. The update package contents can be symbolized as follows:
 
-![](images/PSF1.png)
+![Symbolic representation of update package contents. a box containing two expressions: delta sub zero transform to sub N, followed delta sub N transform to sub zero](images/PSF1.png)
 
 The endpoints that have the base version of the file (V<sub>0</sub>) hydrate the target
 revision (V<sub>N</sub>) by applying a simple transformation:
 
-![](images/PSF2.png)
+![Equation: V sub zero + delta sub zero transform to sub N = V sub n](images/PSF2.png)
 
 The endpoints that have revision N of the file (V<sub>N</sub>), hydrate the target revision
 (V<sub>R</sub>) by applying the following set of transformations:
 
-![](images/PSF3.png)
+![Equation 1: V sub n + delta sub n transform to 0 = V sun 0; Equation 2: V sub zero + delta sub 0 transform to R = V sub R](images/PSF3.png)
 
 The endpoints retain the reverse differentials for the software revision they
 are on, so that it can be used for hydrating and applying next revision update.
@@ -130,11 +130,11 @@ There can be cases where new files are added to the system during servicing.
 These files will not have RTM baselines, thus forward and reverse differentials
 cannot be used. In these scenarios, null differentials will be used to handle
 servicing. Null differentials are the slightly compressed and optimized version
-of the full binaries. It should be noted that update packages can have either
+of the full binaries. Update packages can have either
 forward or reverse differentials, or null differential of any given binary in
-them.
+them. The following image symbolizes the content of a Windows 10 quality update installer:
 
-![](images/PSF4.png)
+![Outer box labeled .msu containing two sub-boxes: 1) Applicability Logic, 2) box labeled .cab containg four sub-boxes: 1) update metadata, 2) content manifests, 3) delta sub RTM transform to sub N (file 1, file2, etc.), and 4) delta sub N transform to RTM (file 1, file 2, etc.)](images/PSF4.png)
 
 ### Hydration and installation