{ "tested_date": "2026-10-14", "browser": "Desktop Codex in-app browser; engine version not recorded", "independent_decoder": "Pillow 11.3.0 and independent PNG/RIFF chunk parsing", "input_samples": 6, "actual_output_samples": 12, "default_quality_92_outputs_byte_match_previous_production": 6, "scope": "Six original synthetic PNG inputs, three quality variants on three inputs; not every browser or source. No competitor conversion tested.", "outputs": [ { "name": "alpha-bands", "quality": 100, "input": "alpha-bands.png", "input_width": 128, "input_height": 64, "input_frames": 1, "input_bytes": 250, "input_sha256": "c3b083ac66c87127db843f9257a5fc52933a8d5e8d82591c7def0e89816ad458", "output": "alpha-bands-q100.webp", "width": 128, "height": 64, "output_frames": 1, "output_bytes": 552, "output_sha256": "a1c18e71b3c96ffac1093b5c2125542bab7b168795046f1bb79cec09dab09259", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8L", "bytes": 50 } ], "input_info": {}, "center_input": [ 32, 152, 112, 128 ], "center_output": [ 32, 151, 112, 128 ], "input_band_centers": [ [ 32, 152, 112, 0 ], [ 32, 152, 112, 64 ], [ 32, 152, 112, 128 ], [ 32, 152, 112, 255 ] ], "output_band_centers": [ [ 0, 0, 0, 0 ], [ 32, 151, 112, 64 ], [ 32, 151, 112, 128 ], [ 32, 152, 112, 255 ] ] }, { "name": "alpha-bands", "quality": 60, "input": "alpha-bands.png", "input_width": 128, "input_height": 64, "input_frames": 1, "input_bytes": 250, "input_sha256": "c3b083ac66c87127db843f9257a5fc52933a8d5e8d82591c7def0e89816ad458", "output": "alpha-bands-q60.webp", "width": 128, "height": 64, "output_frames": 1, "output_bytes": 628, "output_sha256": "22c3d218a021e9a0bfdfde3e2be37efb4cc2a60e929d7fdbb69921ae45c8719c", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "ALPH", "bytes": 32 }, { "type": "VP8 ", "bytes": 86 } ], "input_info": {}, "center_input": [ 32, 152, 112, 128 ], "center_output": [ 31, 151, 113, 128 ], "input_band_centers": [ [ 32, 152, 112, 0 ], [ 32, 152, 112, 64 ], [ 32, 152, 112, 128 ], [ 32, 152, 112, 255 ] ], "output_band_centers": [ [ 0, 0, 0, 0 ], [ 29, 152, 113, 64 ], [ 31, 151, 113, 128 ], [ 32, 152, 112, 255 ] ] }, { "name": "alpha-bands", "quality": 92, "input": "alpha-bands.png", "input_width": 128, "input_height": 64, "input_frames": 1, "input_bytes": 250, "input_sha256": "c3b083ac66c87127db843f9257a5fc52933a8d5e8d82591c7def0e89816ad458", "output": "alpha-bands.webp", "width": 128, "height": 64, "output_frames": 1, "output_bytes": 626, "output_sha256": "443daab0ad125752565bce03e3d6360511d2408388ea5a52f92e27bbc78c030a", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "ALPH", "bytes": 32 }, { "type": "VP8 ", "bytes": 84 } ], "input_info": {}, "center_input": [ 32, 152, 112, 128 ], "center_output": [ 31, 151, 113, 128 ], "input_band_centers": [ [ 32, 152, 112, 0 ], [ 32, 152, 112, 64 ], [ 32, 152, 112, 128 ], [ 32, 152, 112, 255 ] ], "output_band_centers": [ [ 0, 0, 0, 0 ], [ 31, 151, 113, 64 ], [ 31, 151, 113, 128 ], [ 32, 152, 112, 255 ] ] }, { "name": "animated-marker", "quality": 92, "input": "animated-marker.png", "input_width": 48, "input_height": 32, "input_frames": 2, "input_bytes": 355, "input_sha256": "f352082e0d2fb0cf3e1b4c6c4c983ae8b34c9255ff0e7ae2e052850e1e6d3625", "output": "animated-marker.webp", "width": 48, "height": 32, "output_frames": 1, "output_bytes": 574, "output_sha256": "31791712d182c90f230a5c64e2b09bcbfc80cde85de8830b32fe498a0a57e40d", "png_chunks": [ "IHDR", "acTL", "fcTL", "IDAT", "fcTL", "fdAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 72 } ], "input_info": { "loop": 0, "duration": 100.0 }, "center_input": [ 220, 30, 30, 255 ], "center_output": [ 221, 30, 31, 255 ] }, { "name": "colored-detail", "quality": 92, "input": "colored-detail.png", "input_width": 400, "input_height": 160, "input_frames": 1, "input_bytes": 3543, "input_sha256": "544cb2cf1e70209d5aaf956e133271531c114f3d758d8ab5ddcda00aa10f6b5c", "output": "colored-detail.webp", "width": 400, "height": 160, "output_frames": 1, "output_bytes": 3628, "output_sha256": "0ace0a6d8f3c55f35bd212a3196062e1c706595c8a5b2408ef808cc65377e590", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 3126 } ], "input_info": {}, "center_input": [ 255, 255, 255, 255 ], "center_output": [ 255, 255, 253, 255 ], "first_four_stripe_colors": [ [ 140, 34, 141, 255 ], [ 91, 0, 92, 255 ], [ 139, 33, 139, 255 ], [ 90, 0, 90, 255 ] ] }, { "name": "flat-checks", "quality": 100, "input": "flat-checks.png", "input_width": 32, "input_height": 32, "input_frames": 1, "input_bytes": 145, "input_sha256": "a8f7065b8e5e6508dd8df0ced0dbbf2d1dc1d620a72365b36a8fa62c5a9356a8", "output": "flat-checks-q100.webp", "width": 32, "height": 32, "output_frames": 1, "output_bytes": 540, "output_sha256": "69be4046a23a936cfa9479612d02babe60a99dc94fca40c6d8d033ae07da393a", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8L", "bytes": 37 } ], "input_info": {}, "center_input": [ 255, 255, 255, 255 ], "center_output": [ 255, 255, 255, 255 ] }, { "name": "flat-checks", "quality": 60, "input": "flat-checks.png", "input_width": 32, "input_height": 32, "input_frames": 1, "input_bytes": 145, "input_sha256": "a8f7065b8e5e6508dd8df0ced0dbbf2d1dc1d620a72365b36a8fa62c5a9356a8", "output": "flat-checks-q60.webp", "width": 32, "height": 32, "output_frames": 1, "output_bytes": 680, "output_sha256": "e08f074be0c8a29344830ab956eee6603a1dc8af2ef894295551b76307af3703", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 178 } ], "input_info": {}, "center_input": [ 255, 255, 255, 255 ], "center_output": [ 255, 232, 251, 255 ] }, { "name": "flat-checks", "quality": 92, "input": "flat-checks.png", "input_width": 32, "input_height": 32, "input_frames": 1, "input_bytes": 145, "input_sha256": "a8f7065b8e5e6508dd8df0ced0dbbf2d1dc1d620a72365b36a8fa62c5a9356a8", "output": "flat-checks.webp", "width": 32, "height": 32, "output_frames": 1, "output_bytes": 718, "output_sha256": "596a2aed44fcea38eda0af53b75b8b1d94ca14a66f4d0d3b7969a59abfaf81f1", "png_chunks": [ "IHDR", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 216 } ], "input_info": {}, "center_input": [ 255, 255, 255, 255 ], "center_output": [ 255, 233, 243, 255 ] }, { "name": "metadata-note", "quality": 92, "input": "metadata-note.png", "input_width": 96, "input_height": 48, "input_frames": 1, "input_bytes": 307, "input_sha256": "e34c2fb31a96bb921c1cf1e252744167c66857ad9c0b4cefe1487132618a011b", "output": "metadata-note.webp", "width": 96, "height": 48, "output_frames": 1, "output_bytes": 562, "output_sha256": "b026a9f58b63ec4706fb7a92c09601a4624483198fcf9b94888fa65c15dfb8e3", "png_chunks": [ "IHDR", "tEXt", "tEXt", "pHYs", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 60 } ], "input_info": { "Title": "Original metadata boundary", "Comment": "Synthetic sample; not personal information", "dpi": [ 299.9994, 299.9994 ] }, "center_input": [ 32, 152, 112, 255 ], "center_output": [ 32, 152, 112, 255 ] }, { "name": "photo-like", "quality": 100, "input": "photo-like.png", "input_width": 320, "input_height": 192, "input_frames": 1, "input_bytes": 104805, "input_sha256": "332cabc8f9d72a3ac9d7842e44cb50e202a73b37559f9f09c288af44529645e5", "output": "photo-like-q100.webp", "width": 320, "height": 192, "output_frames": 1, "output_bytes": 76966, "output_sha256": "92af8d59eb262251e8aa91bd88edf2a30bd1192d069969b829284589fbe9cc74", "png_chunks": [ "IHDR", "IDAT", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8L", "bytes": 76463 } ], "input_info": {}, "center_input": [ 139, 124, 171, 255 ], "center_output": [ 139, 124, 171, 255 ] }, { "name": "photo-like", "quality": 60, "input": "photo-like.png", "input_width": 320, "input_height": 192, "input_frames": 1, "input_bytes": 104805, "input_sha256": "332cabc8f9d72a3ac9d7842e44cb50e202a73b37559f9f09c288af44529645e5", "output": "photo-like-q60.webp", "width": 320, "height": 192, "output_frames": 1, "output_bytes": 6972, "output_sha256": "db36e33fe852e24dc6ea41bb9e9f2dec1f14cea07e02391c83d32b34f2f1ebd0", "png_chunks": [ "IHDR", "IDAT", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 6470 } ], "input_info": {}, "center_input": [ 139, 124, 171, 255 ], "center_output": [ 130, 113, 160, 255 ] }, { "name": "photo-like", "quality": 92, "input": "photo-like.png", "input_width": 320, "input_height": 192, "input_frames": 1, "input_bytes": 104805, "input_sha256": "332cabc8f9d72a3ac9d7842e44cb50e202a73b37559f9f09c288af44529645e5", "output": "photo-like.webp", "width": 320, "height": 192, "output_frames": 1, "output_bytes": 21476, "output_sha256": "13f00e955bef3030fc4fe47b009fa753f355f2dd0154961eebd76be6c2417716", "png_chunks": [ "IHDR", "IDAT", "IDAT", "IEND" ], "webp_chunks": [ { "type": "VP8X", "bytes": 10 }, { "type": "ICCP", "bytes": 456 }, { "type": "VP8 ", "bytes": 20974 } ], "input_info": {}, "center_input": [ 139, 124, 171, 255 ], "center_output": [ 139, 124, 172, 255 ] } ], "error_cases": [ { "name": "wrong-header", "read_at": "2026-10-14T01:11:34.972Z", "message": "This file is not a valid PNG file.", "downloads": 0, "previews": 0 }, { "name": "truncated", "read_at": "2026-10-14T01:11:35.619Z", "message": "This image could not be opened in this browser.", "downloads": 0, "previews": 0 }, { "name": "oversized", "read_at": "2026-10-14T01:11:36.270Z", "message": "Image dimensions must be at most 4096 pixels per side and 16 million pixels total.", "downloads": 0, "previews": 0 } ] }