Image expectations problem

Attempting to update my CTS to include #1616 leads to some bizarre image expectations.

Here is one of the failures I'm seeing in images/kernel_read_write for CL_FLOAT images:
```
[CL_RG CL_FLOAT 2] - CL_FILTER_LINEAR - CL_ADDRESS_CLAMP - NORMALIZED
FAILED norm_offsets: -0:
Sample 0: coord {-0.007285(-0x1.dd72a6p-8)} did not validate!
Expected (0,0,0,1.0625),
got (0,0,0,1), error of 0
img size 652 (pitch 5216)
Step by step:
Filter denormalizes x to -4.750000, 0.000000, 0.000000 (<-0.007285, 0.000000, 0.000000> * <652.000000, 1.000000, 1.000000>)
Actual integer coords used (i = floor(x-.5)): i0:{ -1, 0 } and i1:{ -1, 0 }
Array coordinate is 0.000000
Sampled pixels (rgba order):
p00: 0.000000, 0.000000, 0.000000, 1.000000
p01: 0.000000, 0.000000, 0.000000, 1.000000
p10: 0.000000, 0.000000, 0.000000, 1.000000
p11: 0.000000, 0.000000, 0.000000, 1.000000
frac( x - 0.5f ) = 0.750000, frac( y - 0.5f ) = 0.500000
ulps: 0.00, 0.00, 0.00, -524288.00 (max allowed: 65538.00)

FAILED: [CL_RG CL_FLOAT 2] - CL_FILTER_LINEAR - CL_ADDRESS_CLAMP - NORMALIZED
```

The A channel for the expectation seems wrong. Am I misinterpreting this message?

Start with the failing case in images/kernel_read_write and reproduce the CL_RG CL_FLOAT normalized linear-filter result described in the report. Compare the generated expectation with the sampled pixels and determine whether the A-channel expectation or the validation behavior is incorrect; done means the failure is explained and the relevant CTS behavior is corrected or documented.

Written by the indexing model from the issue text.