разве ответа не достаточно, что опции pretycolor при использовании splashimage не используется, вместо этого вы можете использовать:
# 'foreground' means the color of the main upper left faces of all letters
# and the big text rectangle that has all our operating system titles in
# it in our GRUB menu.
foreground = DDDDDD
# 'background' sets the colors used in the lower-right 'shadowing' for all
# the letters and the big rectangle around our operating system titles and
# most importantly the hilite (selection) bar that we shift up or down
# with our arrow keys to select an operating system to boot.
background = 000060
#The 'shade' command toggles the shadows to the right-lower side of the rectangle and font.
#shade 0 turns off the shadow effect
#shade 1 turns on the font shadows
shade 1
# 'border' gives us a chance to set a color for any parts of the screen
# not used by the GRUB menu.
# You can pick any colors out of the sixteen color chart here,
# black000000 green008000 silverc0c0c0 lime00ff00
# gray808080o live808000 whiteffffff yellowffff00
# maroon800000 navy000080 redff0000 blue0000ff
# purple800080 teal008080 fuchsiaff00ff aqua00ffff
border 00ff00
# GRUB's viewport command is for controlling the postion and size of the
# rectangle that the text fits inside in the GRUB Menu when we use a
# splashimage. (only available in Graphics mode).
# for example,
# viewport 0 0 66 16
# gives a small rectangle in the upper left of the screen.
# for example,
# viewport 3 3 80 30
# means you will have the largest rectangle in the middle of the screen
# for example,
# viewport 11 6 80 30
# gives you a large rectangle in the lower right of the screen
# The syntax for viewport is like this,
# viewport x0 y0 x1 y1
# The numbers seem to range between,
# viewport 0-11 0-6 66-80 16-30
# x0 sets the left-right positioning for the left side of the rectangle.
# In my tests the smallest number I could set for this parameter was 0 and the largest was 11,
# although sometimes a number less than 11 had to be settled for, depending on the other parameters.
# y0 sets the up and down position for the rectangle.
# 0 entered here makes the rectangle appear as close as possible to the top of the monitor.
# The number 6 was the largest number I could get it to accept, which made the rectangle lower.
# x1 can be in the range from 66-80 and sets the width of the rectangle.
# y1 can be a number in the range between 16 and 30 and sets the height for the rectangle.
viewport 3 2 77 22
у меня работают данные опции, кстати за замещание за постояные апы.