CIFilter.labDeltaE outputs 255 for less than 2% difference in color

[paulz]

CIFilter.labDeltaE().outputImage shows 255 - max color difference:

the above image has dark gray background in preview of the actual image which has transparent background:
https://github.com/paulz/ViewSnapshots/raw/main/AppTests/Snapshots/ToggleView-labDelta.png

Input images:

inputImage
https://github.com/paulz/ViewSnapshots/raw/main/AppTests/Snapshots/ToggleView-intel.png:

image2
https://github.com/paulz/ViewSnapshots/raw/main/AppTests/Snapshots/ToggleView-m1.png

Verified by test:

ViewSnapshots/AppTests/PerceptualDifferencesTest.swift

Lines 66 to 72 in aca7557

	func testLargeDeltaEvenColorDifferenceIsLessThen2Percent() throws {
	let delta = try calculateDelta("ToggleView")
	XCTAssertEqual(areaMaximum(delta.delta), [255, 255, 255, 255])
	let difference = try XCTUnwrap(diff(delta.first, delta.second).outputImage)
	XCTAssertEqual(ImageComparisonResult(difference: difference).maxColorDifference(), 0.015625)
	}

showing that CIFilter.differenceBlendMode is less than 1.5625%
while CIFilter.labDeltaE shows difference RGBA[255, 255, 255, 255]