Guides & how-tos

A Mac screenshot taken in the most compatible format is a PNG, and plenty of upload forms want a JPG. Preview and Finder both convert one with nothing installed. Apple's steps for each, and what happens to transparency.

A Mac opens HEIC photos with nothing installed, and it has three built-in ways to turn one into a JPG. Here is which to use, with Apple's steps for each.

Windows can ask for two Store extensions before it will open a HEIC photo, and opening isn't converting. Here's the route that needs neither.

One Camera setting makes new iPhone photos JPG. A second decides what your computer receives. Neither touches the photos you already took.

Both phones can already make a PDF from a photo, if you know where the option hides. Here are the built-in routes, and when a browser tool is the better pick.

The uncompressed Windows format from the early PC era - why a BMP is enormous, where it still turns up, and what to use instead.

Paint resizes one picture by pixels or percentage, PowerToys resizes a whole selection from File Explorer, and the Photos app is mid-redesign. Here is which to use.

Print sizes are in inches, but image files are in pixels. Here is the conversion for common print sizes, why the shape matters more than the size, and how to set the inches when you print.

The Preview app on iPhone has an Adjust Size option most people never find. Here is how to use it, how to cut the file size too, and when Safari is quicker.

Add up to 50 images, type one width, download one zip. What happens to mixed shapes and small images, and how to match heights instead.

Make it smaller, do it once, and compress last. The four ways a resize quietly costs you quality, and how to avoid each.

Preview resizes the file in place and Photos resizes a copy on export. Here is which to use, how to batch it, and when a browser tool is simpler.

The Preview app on iPhone can export a smaller JPEG with one slider. Apple's steps, how to check the new file size, and what to use when a form sets a hard limit.

Resize to the width the page shows, convert to WebP, and pick the quality once. Why the order matters, and how to check the result.

Preview, Photos and Mail can all shrink an image on a Mac without installing anything. Apple's steps for each, and what to use when a form wants the file under a set size.

A deck or document full of phone photos gets huge fast. Here is how Office's Compress Pictures works on Windows and Mac, and when to shrink the photos before they go in.

A one-click tool gets you under 50KB. But 50KB means two different numbers depending on who counts, and a form that counts the smaller one can still reject the file.

200KB is the most generous of the common upload caps, so it is the one where a scanned certificate or ID keeps its fine text. Here is what to expect.

Look for the original logo file first; cut the background out only when all you have is a flat image. Then check it on black, because logos fail in two predictable places.

Remove the background, click White, download. Which route to take depends on what you start with, and one of them needs no AI at all.

Isolate a product and composite it onto pure white for a marketplace listing, without uploading a shot you haven't launched yet. The White option is the step people miss.

Turn a signature on paper into a clean transparent PNG you can drop onto any document. The trick is a good scan and saving it the right way.

Background removal went from a specialist Photoshop skill to a one-click job. Here's how to get a clean result.

A watermark is a deterrent, not a lock. Here's how to add one that does its job without ruining the photo.

The green card lottery entry takes one photo size only: 600 x 600 pixels, JPEG, 240 kB or less. Here is the State Department spec, who needs a photo, and the mistakes that cost entries.

A passport photo has a pixel size only when a passport office takes a digital upload and publishes one. Here are those numbers, each from the government that sets it, and how print sizes convert.

Since May 2025 a German passport or ID card photo must reach the office digitally, so a print from home no longer works inside Germany. The exception is applying at an embassy abroad.

Ireland sets a size range for printed photos and a pixel floor for Passport Online, and it rejects selfies outright. The full spec from the Department of Foreign Affairs.

Renewing online means uploading an original, unedited file between 54 KB and 10 MB. Renewing by mail means a 2 x 2 inch print. Here is what the State Department lists for each.

A passport photo file has no built-in print size. Here is how to get exactly 35 x 45 mm or 2 x 2 inches out of a home printer, and when not to try.

The difference between mixing light and mixing ink — and why a screen can show colours a printing press physically can't reproduce.

The single coloured square every digital image is built from — what one pixel actually stores, and why you can see them when you zoom in.

One counts the pixels in a digital image; the other counts the ink dots a printer lays down. They get used interchangeably, and here is when that is fine and when it will bite you.

The number behind 'true colour', the 256-colour ceiling on GIFs, and why a smooth sky sometimes turns into visible stripes.

The real amount of detail in an image, counted in pixels — and why it's a different thing from megapixels, DPI, and how big the picture looks on screen.

The reason a punchy photo sometimes turns dull the moment you post it online — a mismatch between the colours your file uses and the ones the web expects.