About JPEG (Joint Photographic Experts Group)
JPEG has been the default way to store photographs since the Joint Photographic Experts Group published the standard in 1992. It uses lossy compression that discards detail your eye is unlikely to notice, trading a small amount of fidelity for dramatically smaller files. Every camera, phone, browser, operating system, and image editor made in the last three decades can open it.
Use JPEG when you need a photo that works everywhere: email attachments, web uploads, application forms, listing photos — anything a recipient must open without thinking about it. It is a poor fit for screenshots, logos, and text-heavy graphics, where its compression leaves visible smudging around sharp edges, and it has no transparency support at all.
Convertmaxxing converts images to and from JPEG entirely in your browser — free, no signup, and nothing is ever uploaded. You can also strip EXIF metadata, such as GPS location, on the way out.
Strengths
- Opens everywhere — the most widely supported image format ever made
- Small files for photographs, with quality you can tune to fit any size budget
- Fast to encode and decode, even for large images
- Decades of tooling — every editor, viewer, and pipeline handles it
Limitations
- Lossy: discarded detail is gone for good, and quality erodes with every re-save
- No transparency support
- Visible artifacts around text, line art, and sharp edges
- Outclassed on size by modern formats — WebP and AVIF are much smaller at the same quality
How JPEG compression actually works
JPEG begins by separating brightness from colour, because human vision is far more sensitive to changes in brightness than to changes in hue. That lets the encoder store colour information at half resolution — a step called chroma subsampling — before it has discarded anything you are likely to notice. It is one of the biggest reasons JPEG files are as small as they are, and also the reason thin red text on a blue background looks smeared when saved as a JPEG.
The image is then cut into 8×8 pixel blocks, and each block is converted from pixels into frequencies using a discrete cosine transform. Smooth gradients become a handful of low-frequency numbers; fine detail becomes high-frequency numbers. The quality setting controls a table of divisors applied to those frequencies, and the high-frequency ones are divided most aggressively, rounding many of them to zero. Long runs of zeros compress extremely well. This also explains what JPEG artifacts look like: blocky 8×8 patches in smooth areas, and ringing halos around sharp edges, because a hard edge needs exactly the high frequencies the encoder throws away first.
Generation loss, and why it matters
Every time a JPEG is decoded, edited, and re-saved, the quantization step runs again on pixels that have already been rounded once. The damage compounds. Save the same photo ten times at quality 80 and the difference from the original becomes obvious; crop and rotate repeatedly and it shows up much sooner. This is what generation loss means in practice, and it is why the durable habit is to keep an untouched original and export copies from it rather than editing the same JPEG over and over.
A common misunderstanding follows from this. Converting a JPEG to PNG or TIFF does not restore anything — lossless formats faithfully preserve whatever pixels they are handed, artifacts included. The conversion is genuinely worth doing when you are about to make many successive edits and want to stop the degradation accumulating, but the detail discarded on the first save is not recoverable by any tool, on this site or anywhere else.
Frequently asked questions
- Is JPG the same thing as JPEG?
- Yes — identical format, two spellings. Early versions of Windows and DOS limited file extensions to three characters, so .jpeg was truncated to .jpg, and both conventions stuck. Any software that opens one opens the other, and renaming between them changes nothing about the file contents.
- What quality setting should I use?
- For photographs, 80 to 85 is the usual sweet spot: the difference from 100 is invisible at normal viewing sizes while the file is a fraction of the size. Below about 70 you start to see blocking in smooth areas like skies and skin. Above 90 the file grows quickly for a gain almost nobody can perceive. If the image contains text or a screenshot, no JPEG quality setting will look truly clean — use PNG instead.
- Can a JPEG have a transparent background?
- No. JPEG has no alpha channel and no version of the format adds one. When you convert an image with transparency to JPEG, the transparent areas must be filled with a solid colour, usually white or black. If you need transparency, convert to PNG or WebP, both of which support it fully.
- How do I remove GPS location data from a JPEG?
- Photos taken on a phone typically embed EXIF metadata containing the coordinates where the shot was taken, along with the device model and timestamp. Convertmaxxing can strip that metadata during conversion so the file you download carries the image and nothing else. Stripping also removes the embedded colour profile and orientation tag, which is why the converter applies rotation to the pixels first — otherwise a stripped photo could come out sideways.