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Why coloured fine text can blur in a JPEG photo strip
JPEG may preserve brightness detail more strongly than colour detail.
A small coloured caption can look softer than nearby black text after JPEG export. The format may reduce colour detail more aggressively because human vision is less sensitive to some colour differences than luminance detail.
Check the type of detail
Many JPEG workflows use chroma subsampling, which stores colour information at lower spatial resolution than brightness information. Fine saturated text on a contrasting background can therefore show colour bleed or softened edges even when the portrait looks acceptable.
Evidence: Imaging software documentation
Inspect at the delivered size
Export the strip at its final pixel dimensions and inspect the caption at actual viewing size. Compare a neutral dark caption with the coloured version. Do not judge from an enlarged editor preview, which may hide resampling and compression behaviour.
Select a more robust design
Use larger text, higher contrast and simpler letter shapes when captions must remain readable after compression. A lossless PNG can preserve sharp edges, though it may create a larger file. Test the actual messaging or print route before settling on an output format.
Evidence: Web standard
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- Adobe, JPEG Compression AttributesImaging software documentation
- W3C, Portable Network Graphics Specification, Third EditionWeb standard