Why convert a PNG to TIFF
PNG and TIFF are both lossless, so the picture itself doesn't get better or worse. What changes is who will accept it. Print shops, publishers, stock libraries, archives and some scanning and layout software ask for TIFF specifically, often "at 300 DPI", and some want a transparent background kept for logos and cut-outs. This converter is built for that hand-off: it keeps what the PNG has, tells you what's in the file, and checks the result.
Transparency, kept exactly
A transparent PNG becomes a TIFF with an alpha channel, stored the same way PNG stores it: each pixel's colour as it is, plus how see-through it is. Software that understands transparency in TIFFs shows it; software that doesn't simply ignores the extra channel. If the place you're sending it to can't handle transparency, choose Fill with white.
The detail that most converters get wrong is the soft edge: anti-aliased outlines, drop shadows and glows, where pixels are only partly transparent. A common way to convert in a browser is to draw the PNG on a canvas and read the pixels back. The canvas stores colours already multiplied by their transparency, so reading them back rounds them, and the fainter the pixel, the bigger the error. We measured that route on a test image with a soft shadow:
| How transparent the pixel is | Colour changed through a canvas | Largest change (out of 255) |
|---|---|---|
| Almost invisible (alpha 1–15) | 4,856 of 4,856 pixels | 127 |
| Faint (alpha 16–63) | 13,357 of 13,412 | 8 |
| Mostly solid (alpha 64–254) | 19,647 of 23,652 | 2 |
| Fully transparent | 23,615 of 23,615 set to black | — |
On screen over white, a change in an almost invisible pixel is hard to see. It shows up when the TIFF is placed over a dark background, or when someone in a print or design workflow adjusts the transparency. This converter decodes the PNG itself instead of going through the canvas, so all 41,920 partly transparent pixels in that image reached the TIFF with exactly the PNG's values.
16-bit PNGs stay 16-bit
PNGs exported from photo editors, scanners and scientific cameras can be 16 bits per channel: 65,536 levels instead of 256, which matters for smooth gradients, skies and later editing. A canvas only holds 8 bits, so canvas-based converters quietly cut that down: our 16-bit test image had 11,193 different red values, and after a canvas, 256. Here a 16-bit PNG becomes a 16-bit TIFF, greyscale or colour, with or without transparency. If your software only opens 8-bit TIFFs, choose Always 8-bit.
DPI, colour profile and compression
If the PNG records a resolution, the TIFF gets the same DPI; otherwise it's set to 72, the usual default, and you can pick 300 or any value for print. DPI only says how large the image prints; the pixels aren't resampled, and each result shows the printed size. An embedded colour profile is copied into the TIFF unchanged.
All three compression options are lossless. LZW is the one every program opens. ZIP was smaller in our tests, by about a quarter on a 16-bit image and by almost half on the soft-shadow image. None is for the rare system that can't read compressed TIFFs. Greyscale PNGs stay single-channel greyscale TIFFs, and palette PNGs are expanded to full colour, since that's what TIFF readers expect.
Checked before you download it
Every TIFF is read back with a separate TIFF decoder and compared with the PNG, value by value. The result says "every pixel matches the PNG", or exactly what didn't. We also opened every test file with tifffile, an independent reader based on the same rules as libtiff, and compared it with the known pixel values: greyscale at 2 and 16 bits, palette with transparency, colour-keyed transparency, interlaced PNGs, and 8- and 16-bit RGBA all matched exactly. Several PNGs can be converted at once, or combined into one multi-page TIFF, and nothing is ever uploaded.