CIFilter.labDeltaE outputs 99 for not noticeable difference in color

[paulz]

CIFilter.labDeltaE outputImage example shows 2 pixel difference:

the above image has dark gray background in preview of the actual image which has transparent background:

https://github.com/paulz/ViewSnapshots/blob/main/AppTests/Snapshots/ContentView-labDelta.png:

at CGPoint(x: 108, y: 28) CIFilter.labDeltaE shows difference RGBA[99, 99, 99, 99]

while CIFilter.labDeltaE().inputImage at that point has color: RGBA[79, 63, 0, 255]
and CIFilter.labDeltaE().image2 at that point has color: RGBA[79, 62, 0, 255]

Input images:

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

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

Verified by test:

ViewSnapshots/AppTests/PerceptualDifferencesTest.swift

Lines 74 to 90 in 37a518e

	func testLargeDifferenceEvenWhenColorHasNoDifference() throws {
	let delta = try calculateDelta("ContentView")
	let maxDifference: [UInt8] = [99, 99, 99, 99]
	XCTAssertEqual(areaMaximum(delta.delta), maxDifference)
	let diffPoint = CGPoint(x: 108, y: 52 - 24)
	let maxColor = getColor(delta.delta, at: diffPoint)
	XCTAssertEqual(maxColor, maxDifference)
	let firstColor = getColor(delta.first, at: diffPoint)
	XCTAssertEqual(firstColor, [79, 63, 0, 255])
	let secondColor = getColor(delta.second, at: diffPoint)
	XCTAssertEqual(secondColor, [79, 62, 0, 255])
	let difference = try XCTUnwrap(diff(delta.first, delta.second).outputImage)
	XCTAssertEqual(ImageComparisonResult(difference: difference).maxColorDifference(), 0)
	}

[paulz]

Filed feedback issue: https://feedbackassistant.apple.com/feedback/10162578