Another way of looking at compression
Lossy compression and paraphrase both work on the principle of converting expression to ideas and then back to expression. Here are some examples to demonstrate their similarity:
- MP3: convert expression (waveform samples) to ideas (frequency intensities) back to expression.
- JPEG: convert expression (blocks of pixels) to ideas (intensities) back to expression.
- MIDI: convert expression (waveform samples) to ideas (notes) back to expression.
- OCR: convert expression (pixels) to ideas (characters and glyphs) back to expression.
- Paraphrase: convert expression (text) to ideas (facts) back to expression. This is the basic premise of node what you don't know, research papers, and language translation.
- Reverse engineering: convert expression (hardware or software) to ideas (algorithms and interfaces) back to expression.
- Fanfiction: convert expression (a story) to ideas (character traits) back to expression.
Copyright law forbids copying of expression without permission of the copyright owner. The derivative works clause prohibits paraphrase in cases where too much expression survives the paraphrase; only a judge can draw the line between idea and expression.