jpg compression artifact

JPEG compression artifacts are visual distortions that occur when an image is compressed using the JPEG format, which is lossy compression method. These artifacts become more pronounced at lower quality settings or with repeated saving.
What Are JPEG Compression Artifacts?
• Blockiness: JPEG divides images into 8×8 pixel squares, and heavy compression can cause visible edges or “blocks” between these squares, especially in areas with smooth gradients (e.g., skies).
• Color Banding: Subtle color transitions may appear as distinct bands due to reduced color information.
• Blurring: Fine details can be lost, making edges or textures appear soft or smeared.
• Noise or Halos: Around high-contrast edges, you might see ringing or halo-like effects.–Mr. Grok

Rainbow Tilly

dog linoleum
My dog likes crayons. Really, what could go wrong?

“We have ensured that our products are safe since 1903, when we first began offering crayons. All Crayola and Silly Putty products have been evaluated by an independent toxicologist and found to contain no known toxic substances in sufficient quantities to be harmful to the human body, even if ingested or inhaled.”–Crayola

robin egg blue

a robin's egg and some old govt correspondence
Michael Carrithers commented that b&w photos of rust are not entirely informative. I am taking his words as an invitation.
Despite my monochromatic preference (“friends don’t let friends shoot colour”), I am falling off the wagon for a few days, into the chaos and mess, 390 to 750 nanometers.
Blue egg of Robin largely meaningless in b&w would be.