Find files, editable templates and browser test targets by what you need to make or test. The directory below is cut by format; the two collections under it cut the same library by subject and by workflow.
The same 512x341 photograph written as jpeg progressive. Progressive scan order, which a naive reader renders as a blurry first pass or not at all. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as jpeg q60. Baseline JPEG at quality 60. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as jpeg q92. Baseline JPEG at quality 92. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as pgm binary. Greyscale Netpbm. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as png 24bit. The lossless reference for this group; every lossy member is scored against it. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as png grayscale. Single channel, so a reader assuming three will read past the end of a row. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as png interlaced. Adam7 interlacing decodes in seven passes rather than one, which is a separate code path. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as png palette256. A palette PNG carries indices and a colour table, not RGB pixels. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as ppm binary. Netpbm binary: a tiny header then raw bytes, with no compression at all. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tga rle. Run-length encoded Targa. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tiff 16bit gray. 16 bits per sample: a reader that truncates to 8 loses half the range silently. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tiff deflate. Deflate inside TIFF. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tiff jpeg. A lossy JPEG stream inside a TIFF container, which breaks the assumption that TIFF is lossless. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tiff lzw. LZW, the TIFF compression most readers assume. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as tiff uncompressed. Raw strips, the simplest TIFF and the largest. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as webp lossless. Lossless WebP, a different bitstream from the lossy one. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same 512x341 photograph written as webp lossy. Lossy WebP. Every member of this group is identical pixels, so a decoder returning different dimensions or a different pixel count has lost something rather than simply produced a different file; the 24-bit PNG in this group is lossless and is the reference the lossy members are measured against Source plate t-grad-cool.
The same plate encoded once at JPEG quality 25. Blocking and ringing are bounded by that single pass, so a restorer can be scored against the PNG reference in this group rather than against an opinion Plate t-grad-warm.
The same plate encoded once at JPEG quality 50. Blocking and ringing are bounded by that single pass, so a restorer can be scored against the PNG reference in this group rather than against an opinion Plate t-grad-warm.
The same plate encoded once at JPEG quality 75. Blocking and ringing are bounded by that single pass, so a restorer can be scored against the PNG reference in this group rather than against an opinion Plate t-grad-warm.
The same plate encoded once at JPEG quality 90. Blocking and ringing are bounded by that single pass, so a restorer can be scored against the PNG reference in this group rather than against an opinion Plate t-grad-warm.
A synthetic photographic plate of a smooth abstract gradient, 1024x683, lossless PNG. This is the reference every lossy variant in this group is derived from Plate t-grad-warm.
The same plate encoded once at JPEG quality 25. Blocking and ringing are bounded by that single pass, so a restorer can be scored against the PNG reference in this group rather than against an opinion Plate t-grad-mono2.
