Blog
18 posts
Writing.
Notes on file formats, privacy and the small problems these tools exist to solve.
Does Cropping Shrink a Photo?
A 16px trim grew 7 of 7 JPEGs at q95 (median 1.5036x). Cropping is a re-encode; the scissors do not set the bytes.
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Why does this JSON validate in one tool and fail in another?
A UTF-8 BOM turns a 34-byte valid object into 37 bytes. jq passes; browser JSON.parse fails at U+FEFF. A valid stamp is a parser’s stamp.
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Is a photo of your signature a signature file?
No. A page photo is a grey rectangle on the line. A stand-in page was 898,344 bytes; transparent ink PNG was 65,709. The win is missing paper.
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Does converting a JPG to WebP shrink the file?
On 7 photos, lossy WebP q80 was a median 44.3% of the JPG. Lossless WebP was 414.6%. One toggle, opposite outcomes.
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Does removing EXIF shrink a photo?
A real iPhone photo had 9,975 bytes of EXIF including GPS. A lossless strip saved exactly that. A canvas re-save at quality 95 grew 24%.
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If you draw a black box on a PDF, is the text gone?
No. A black rectangle sits on top of the text. pdftotext still returns Account 4417-2291. Covering is not removing.
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If I resize a photo to 50%, is the file half the size?
50% of each side is 25% of the pixels. 17 photos landed at a median 25.4% of original bytes, not 50%.
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Should you convert a screenshot to JPEG?
A photo as PNG was 2,285,876 bytes; JPEG quality 85 made 320,385. A spreadsheet UI screenshot went from 68,660 PNG to 117,944 JPEG. Convert photos, not flat UI.
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Why is my PDF over 5MB?
A 6-page photo packet printed to PDF was 6,447,273 bytes. Re-encoding the pictures at the same 1870x2420 grid landed at 4,279,341, under the 5,000,000-byte portal cap.
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Does 300 DPI make a bigger file than 72 DPI?
Same 1200×1800 JPEG at 72 DPI and 300 DPI: both 103,977 bytes. A 4×6 at 300 DPI is 17× the pixels of 72 DPI. DPI is a print label, not a file-size knob.
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Your US passport photo does not have to be 600 pixels
A 4032×2678 phone JPEG was 1,182,975 bytes and already passed online renewal. Resizing it to 600×600 made a 40,007-byte file under the 54 KB floor. 600×600 is the visa spec.
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I compressed 9 images to 100 KB. Here's what survived.
A 1,609,228-byte food photo shrank to 1749×1749 at JPEG quality 20 to hit 99,927 bytes. Seven photos all landed at quality 20–25. 100 KB is 102,400 bytes.
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