How to use
- Render page 1 of the A4 report at scale 1 for a 595 by 842 PNG.
- Render page 2 of the Letter invoice at scale 1 for a 612 by 792 PNG.
- Treat the PNG as paint. Do not expect a text search to find the sentence.
Formula / how it works
Page 1 of report-a4-3pages.pdf at scale 1 is a PNG of 595 by 842 pixels. The points are 595.28 by 841.89, and the canvas rounds them. Page 2 of invoice-letter-2pages.pdf at scale 1 is 612 by 792, which is US Letter with no rounding to do. Both downloads are PNG, so the flat white of the page and the black of the Helvetica sentence are not put through a JPEG quantiser.
pdf.js draws the one page you named. The canvas encodes PNG. There is no pdf-lib step, because the file you save is an image. The sentence on the page is paint. A search in a photo app will not find "report-a4-3pages.pdf page 1" inside the PNG.
Scale stays between 0.5 and 4. This sample used 1 so the pixels match the points as closely as rounding allows. Quality is not a field, because PNG is lossless. A faint grey from text hinting is still stored exactly as the canvas produced it.
Use the JPEG page when you want a smaller file and you can accept blockiness on the letters. Use this page when a ticket or a slide needs the letters to stay sharp. Use the compressor when every page should become a picture and then go back into a PDF. A password stops the render before any pixel is written.
The A4 PNG is 595 by 842 because 595.28 rounds to 595 and 841.89 rounds to 842. The Letter PNG is 612 by 792 with nothing to round. Neither file is a JPEG, so the Helvetica stroke is not broken into blocks. Scale 1 was the sample. Scale 2 would roughly double both sides and the file would get heavier, which is the trade the JPG page already showed at 1191 by 1684. A password still stops the render before a pixel is stored.
A JPEG of one page is PDF to JPG. Wrapping pictures back into a PDF is the PDF compressor JPEG rebuild.
Worked examples
A4 page at scale 1
Inputs: p2n-f: report-a4-3pages.pdf | p2n-page: 1 | p2n-scale: 1
On this page, take report-a4-3pages.pdf, then 1, then 1 and press Convert to PNG. Expect whole pixels, with A4 points rounded.
Result: PDF to PNG: page 1 of 3, 595×842 PNG. 18.7 KB
The download is a picture of that page. Words in the picture cannot be selected.
Letter page 2 at scale 1
Inputs: p2n-f: invoice-letter-2pages.pdf | p2n-page: 2 | p2n-scale: 1
On this page, take invoice-letter-2pages.pdf, then 2, then 1 and press Convert to PNG. Expect whole pixels, with A4 points rounded.
Result: PDF to PNG: page 2 of 2, 612×792 PNG. 18.9 KB
The download is a picture of that page. Words in the picture cannot be selected.
Use cases
- Keeping sharp letters when a JPEG would blur them.
- Matching Letter pixels to Letter points at scale 1.
- Checking the rounded A4 size, 595 by 842, against 595.28 by 841.89 points.
- Stopping cleanly when a PDF asks for a password.
Tips & limitations
- PNG has no quality slider on this page.
- Scale 2 would be about 1191 by 1684, the same scale the JPG page demonstrated.
- One page per download.
- The worker for pdf.js loads with this page only.
FAQ
Why is the A4 PNG 595 by 842 rather than 595.28 by 841.89?
The canvas needs whole pixels. 595.28 rounds to 595 and 841.89 rounds to 842.
Why is the Letter PNG exactly 612 by 792?
Those page points are already whole numbers, and the scale was 1.
Is the sentence still selectable?
No. It is paint in the PNG. The JPG page has the same limit, with JPEG loss on top.
Can I render every page at once?
Not here. Name the page. A zip of every page is a different control.
Does a password get rendered?
No. The render stops before the canvas is filled.
When would I pick JPEG instead?
When the file size matters more than the edges of the letters. Quality 80 on the JPG page made a 21.7 KB A4 picture at scale 2.
595 by 842 is report-a4-3pages.pdf page 1 at scale 1. A cropped page will not land on those pixels.