So... Why not use the new export function? That also supports scaling down. All that said, I feel your pain, because Photoshop isn't exactly a forerunner in optimizing low resolution pixel art or downscaling larger version for prep to low resolution export, nor for colour reduction or file size optimization. Myself, I avoid Photoshop entirely and rely either on Color Quantizer (for exact colour reduction control) or Squoosh. (Also use PhotoLine, which has good export options for pixel art.) Both allow for what you need to do. Squoosh also runs as an off-line app, but requires a local LAMP web server to run it in. CQ is a desktop app for Windows, but is predominantly PNG optimization oriented, while Squoosh supports the latest AVIF, OxiPNG, and other file formats. https://squoosh.app/ http://x128.ho.ua/color-quantizer.html
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