A mask has numerical class values as well as a visual appearance. A black-and-white preview alone does not prove those values survived.
Keep the decoded value contract
A lossless image format can preserve encoded raster samples through its compression and reconstruction. The chosen sample representation and decoding route still matter for a mask's numeric meaning. A later color conversion, rescaling or threshold can change class values outside the lossless compression step itself. Primary reference: W3C PNG lossless raster storage.
For an original mask-storage worksheet, specify expected decoded type and foreground values. Retain the encoder input array and compare decoded samples using the intended route. A display that renders two values as black and white does not prove that their numeric class codes are identical.
Compare fictional binary encodings
Take an invented class mask [0,1,0,1]. A matched lossless integer encode/decode route should retain those four values for this stated contract. If a separate preprocessing step maps foreground 1 to display value 255 before encoding, lossless reconstruction can correctly return [0,255,0,255] instead.
That second route preserved its encoder input but changed the original class code before storage. A receiver testing equality with 1 would then behave differently. The original exercise assumes the defined integer route and does not guarantee every application preserves palette, bit-depth or color-processing choices unchanged.
Verify samples rather than screenshots
Prepare an original round-trip record with the before-encoding values, encoded representation and decoded values. Separate compression reconstruction from any rescaling performed by the viewer or application. Retain an explicit foreground interpretation when masks move between numeric processing and presentation tools.
This guide recommends no HM storage product and gives no inspection acceptance rule. Its reader decision is whether discrete class values survive the complete route, not merely whether the compression method is lossless. Class-code preservation should be verified before a decoded mask is used as the same segmentation evidence.
Customer Questions
What values are expected under the first fictional contract?
[0,1,0,1].
Can lossless storage preserve a separately rescaled input of 255?
Yes, without restoring the earlier class code one.
Does a black-and-white preview prove numeric identity?
No. Decoded samples need comparison.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
Discuss Your Machine Requirement
Share your product, container, required output and the evidence needed for your technical review.
Request a Technical Review