PocketBook: use inkview to adjust image colors to look more bright (#9756)

Adjust image colors for PocketBook color devices to supply
brighter image colors. Make it a config option so we can
adjust it to a sensible default for all devices later.
Also enable HW Dithering for color devices: the dithering
flag allows us to figure out if what is viewed is an
image or text. This way we can enable color rendering
or not based on the dithering flag.

frontend/device/pocketbook/device.lua

@@ -561,7 +561,9 @@ local PocketBook632 = PocketBook:extend{
 local PocketBook633 = PocketBook:extend{
     model = "PBColor",
     display_dpi = 300,
+    color_saturation = 1.5,
     hasColorScreen = yes,
+    canHWDither = yes, -- Adjust color saturation with inkview
     canUseCBB = no, -- 24bpp
     isAlwaysPortrait = yes,
     usingForcedRotation = landscape_ccw,
@@ -625,7 +627,9 @@ local PocketBook740_2 = PocketBook:extend{
 local PocketBook741 = PocketBook:extend{
     model = "PBInkPadColor",
     display_dpi = 300,
+    color_saturation = 1.5,
     hasColorScreen = yes,
+    canHWDither = yes, -- Adjust color saturation with inkview
     canUseCBB = no, -- 24bpp
     isAlwaysPortrait = yes,
     usingForcedRotation = landscape_ccw,
@@ -640,7 +644,9 @@ end
 local PocketBookColorLux = PocketBook:extend{
     model = "PBColorLux",
     display_dpi = 125,
+    color_saturation = 1.5,
     hasColorScreen = yes,
+    canHWDither = yes, -- Adjust color saturation with inkview
     canUseCBB = no, -- 24bpp
 }
 function PocketBookColorLux:_model_init()