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Ecommerce Glossary

Photo Compression, Image Formats and EXIF: JPG, PNG, WebP, HEIF

Updated: 14 October 2026

Photo compression reduces the file size of an image: lossless compression (PNG) keeps every pixel, while lossy compression (JPG, WebP, AVIF, HEIC) discards detail the eye barely notices. This page also covers image file formats, EXIF metadata, photo optimisation for online shops and Google's advice on images.

Photo compression: lossy and lossless

Photo compression is storing the same image in fewer bytes so the file gets lighter. Lossless compression rebuilds every pixel exactly, while lossy compression throws away detail the eye rarely notices in exchange for a much smaller file.

Every product photo in an online shop has been compressed somewhere along the way. The real questions are how hard and by which method, because that decides whether the weave of a fabric and the clean edge of a box survive while the page still loads quickly.

Type	What it does to the image	Typical formats	Best for
Lossless	stores the data more efficiently; the decoded image is identical to the one you saved	PNG, lossless WebP	logos, graphics with text, screenshots, cut-out products
Lossy	simplifies the image and discards fine detail, depending on the quality setting	JPG, lossy WebP, AVIF, HEIC	product photos for your website, marketplaces and social media

JPG shows the mechanism most clearly. The format splits the image into 8 × 8 pixel blocks, converts each block with a discrete cosine transform and rounds off the components the eye is least sensitive to, and the "quality" slider in your editor sets how aggressively. According to the overview of the JPEG format, a 10:1 compression ratio usually gives an image you cannot tell apart from the original by eye.

Orchid on a purple background split into four quarters saved at 0, 30, 60 and 90 per cent compression

How to spot over-compression

Blocking - visible 8 × 8 px squares on smooth backgrounds and flat surfaces.
Halos and noise around sharp, high-contrast edges, most obvious on label text.
Banding in tonal gradients, for example in the soft shadow under a product.
Smeared texture - fabric, leather or brushed metal lose exactly the detail that sells the product.

The most common mistake is re-saving the same JPG again and again. Every recompression costs a little quality, so make your edits on the source file or a lossless copy and export the JPG once, at the very end.

The second is compressing instead of resizing: a 6000 px photo shown in an 800 px slot will be too heavy at any quality setting. The order never changes: resize first, then compress. You can resize an image online for free with our tool before you export the final file.

What to compress with

Squoosh - a free browser app that does all the work locally, so your images never leave your device, with a before-and-after preview.
The export dialog in Photoshop, Lightroom or GIMP - a quality slider and a file-size preview before you save.
Automatic conversion in your shop platform or an image CDN - handy for hundreds of photos, but check a few results at 100% zoom.

From the studio: by default we deliver JPGs at 2000 × 2000 px, 72 DPI, RGB, ready to upload to your shop. For a printed catalogue there is the 6K Resolution add-on (6000 px, 300 DPI), because no conversion later on can add detail that was never in the file.

Image file formats: JPG, WebP, AVIF, PNG, HEIF and RAW

An image file format defines the type of compression, the colour depth and whether the file can carry transparency and metadata. Product photos on websites are saved today as JPG, WebP or AVIF, while graphics and cut-out products go into PNG.

Format	Compression	Transparency	Browsers	Use
JPG	lossy	no	all	product photos, marketplaces, sending files to clients
WebP	lossy or lossless	yes	Chrome, Edge, Firefox, Opera, Safari 14+	photos on your shop website
AVIF	lossy or lossless (AV1 codec)	yes	Chrome 85+, Firefox 93+, Safari 16.1+, Edge 121+	web photos where every kilobyte counts
PNG	lossless	yes, full alpha channel	all	logos, graphics with text, products on a transparent background
HEIC (HEIF)	lossy (HEVC codec)	yes	Safari 17+ only	photos stored on a phone, not on a website
RAW	unprocessed sensor data	not applicable	not displayed	source material for editing

JPG was standardised in 1992 (ITU-T T.81, later ISO/IEC 10918-1), and the JPEG Committee still calls it the most dominant still image format around. Any program will open it. What it lacks is an alpha channel, so it cannot store a transparent background.

Google's own figures put lossy WebP at 25-34% smaller than a comparable JPG and lossless WebP at 26% smaller than PNG. AVIF squeezes files further, but MDN points out that it does not render progressively: the browser shows the picture only once the whole file has downloaded.

RAW is not a finished photo but unprocessed data from the camera sensor, in a manufacturer's format (Canon CR3, Nikon NEF, Sony ARW, Fujifilm RAF) or in the open DNG format Adobe introduced in 2004. It typically records 12 or 14 bits per pixel, so white balance can be corrected after the shoot without loss, but the file always has to be processed and exported to JPG, WebP or PNG before it goes online. More in our guide what RAW files are and how to open them.

PNG format

PNG (Portable Network Graphics) is a raster format with lossless compression and a full alpha channel, which means smooth, graded transparency. It was created as a patent-free replacement for GIF, and the W3C approved its specification on 1 October 1996.

PNG compression works in two steps: a filter applied to each row (one of five: None, Sub, Up, Average, Paeth), then the Deflate algorithm. The decoded file matches the saved one exactly, but a photo full of gradients and texture weighs far more as a PNG than as a well-exported JPG. In June 2025 the W3C published the third edition of the specification, which formally adds animation (APNG), HDR and Exif metadata.

Monitor displaying the .png file extension on a white screen

When PNG makes sense for product photos

A cut-out product that a designer will place on a banner or a page in a different colour.
Logos, icons and graphics with text when you have no vector version.
Screenshots and intermediate files that still need editing.

The classic mistake is a PNG with a plain white background: the same picture as the JPG, several times heavier and with no benefit at all. If you cut out products yourself, compare the best AI apps for removing backgrounds online and always check the edges at full zoom.

From the studio: packshots ordered with the Remove background add-on (see our product photography pricing) are delivered as PNG files with a transparent background, because JPG has no alpha channel. For a product page on white, the standard JPG is all you need.

HEIF and HEIC

HEIF (High Efficiency Image File Format) is an image container developed by MPEG and defined in ISO/IEC 23008-12, with the technical work completed in 2015. A HEIF file whose image is encoded with the HEVC (H.265) codec is a HEIC file, the format iPhones have used for photos since iOS 11.

The container can hold more than one image: a burst sequence, a transparency layer or a depth map. A HEIC photo needs roughly half the storage of a JPG of similar quality (the estimate quoted in the overview of the HEIF format), which is why your phone fits so many more pictures.

HEIC or JPG?

Feature	HEIC	JPG
File size at similar quality	about half	baseline
Transparency, bursts, depth maps	yes	no
Browsers	Safari 17+ only (about 17% of users worldwide according to Can I use, October 2026)	all
Licensing	HEVC codec covered by patents	no practical restrictions

For sellers the conclusion is simple: HEIC is a good format for keeping photos on a phone, not for uploading to your own shop. Chrome, Edge and Firefox won't display it, and Google doesn't list it among the formats supported in Google Images.

Marketplaces are a separate case. eBay UK lists HEIC among its accepted upload formats, alongside JPEG, PNG, WebP and AVIF, so a phone shot can go straight into a listing. Your own product pages cannot rely on it.

How to convert HEIC to JPG

iPhone, new photos: Settings > Camera > Formats > Most Compatible. The camera then saves JPGs.
iPhone, transfer by cable: photos imported to a computer over USB may be converted to JPG on the way; the Keep Originals option in the Photos settings switches that conversion off.
Mac: open the file in Preview, choose File > Export and pick JPEG as the format.

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EXIF: the metadata inside a photo

EXIF (Exchangeable Image File Format) is the metadata standard a camera or phone writes into a photo file: the date, the camera and lens model, shutter speed, aperture, ISO, orientation and often GPS coordinates. The first version appeared in 1995, and the current one, Exif 3.1, was published by the Japanese camera industry association CIPA in January 2026.

EXIF lives in JPG and TIFF files, and also in WebP (a dedicated chunk in the file container) and PNG (the eXIf chunk described in the 2025 W3C specification). The claim in older guides that PNG and WebP "don't support EXIF" is out of date.

EXIF field	What it records
Make, Model	camera manufacturer and model
LensModel, FocalLength	lens and focal length
ExposureTime, FNumber, ISOSpeedRatings	shutter speed, aperture, ISO sensitivity
DateTimeOriginal	date and time of capture by the camera clock (time zone offsets only since version 2.31 of July 2016)
Orientation	how to rotate the image for display
GPSLatitude, GPSLongitude	where the photo was taken
Artist, Copyright	author and copyright notice

How to view EXIF data

Windows: right-click the file > Properties > Details tab.
macOS: in Finder choose File > Get Info and open More Info (as in the screenshot above), or open the photo in Preview and choose Tools > Show Inspector.
Phone: open the photo in your gallery and swipe up or tap the info icon.
Every field, including manufacturer-specific data: ExifTool, or the metadata panel in Lightroom and Capture One.

EXIF and product photos

For a photographer, EXIF is a shoot log: the settings behind a good frame are easy to repeat for the next batch of products. For a shop, the field that matters most is Orientation. If an export tool strips it without rotating the pixels, a phone photo can end up on its side.

Before you upload a phone photo to a listing, check the GPS data: the coordinates show where the shot was taken, which may well be your home. Some services strip metadata on upload and some keep it, so it is safer to clean the file yourself. In ExifTool, exiftool -all= photo.jpg removes the metadata and keeps a backup copy with "_original" added to its name.

Google reads the creator and licence of a photo from IPTC metadata embedded in the file or from structured data on the page, as explained in the Image SEO section below. If you sell second-hand from your phone, our Vinted photo tips cover lighting and framing as well.

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Photo optimisation for online shops

Photo optimisation (photo optimization in US spelling) means preparing an image for publication so that it weighs as little as possible while still looking good enough for the viewer. It covers pixel dimensions, file format, compression level and the way the image is embedded on the page, so compression is only one of the steps.

Google's documentation for Google Images notes that images are often the largest contributor to overall page size. On a product page the main photo is often the largest element visible on load, and then it sets the Largest Contentful Paint (LCP). According to web.dev, a good LCP is 2.5 seconds or less, measured at the 75th percentile of page loads.

Photo optimisation step by step

Dimensions. Scale the photo to the largest size at which it actually appears, with some headroom for high-density screens. On screen it is pixels that count, not the DPI value stored in the file.
Format. WebP or AVIF on your website, JPG as the fallback, PNG only for transparent backgrounds.
Quality. Lower the quality slider until the first artefacts appear on edges and smooth backgrounds, then go back one step. Judge at 100% zoom.
Responsive versions. The srcset and sizes attributes or a <picture> element, always with a fallback URL in src, as Google recommends.
Loading. loading="lazy" for images further down the page, never for the main photo visible straight away. The width and height attributes reserve space for the image, so the layout doesn't jump.
Checks. Lighthouse and the Performance panel in Chrome DevTools flag files that are too heavy, images larger than their display size and formats worth switching to WebP or AVIF.

Photo file size before and after optimisation

Typical mistakes are uploading files straight from the camera, lazy-loading the main product photo and recompressing the same JPG after every small edit.

Marketplaces set their own rules

Marketplaces process uploads themselves, so there the priority is a sharp source file that is large enough. eBay UK asks for at least 500 × 500 px, recommends about 1600 × 1600 px and accepts files of up to 12MB. Our standard 2000 × 2000 px JPG is already above that recommended size.

Image SEO: product photos for Google

Image SEO is optimising images for search engines: descriptive file names, alt text, placing each image next to relevant text, a supported format and fast loading. It helps Google understand what a photo shows and display it in Google Images.

What Google recommends

Alt text is, according to Google, the most important attribute for describing an image. It should say what is in the picture; filling it with keywords may get the site treated as spam.
File name: short and descriptive, such as "black-ceramic-mug.jpg" rather than "IMG_2011.jpg". The extension should match the file type.
Context: place the photo near the text it relates to. Google also takes information from captions and image titles.
Formats supported in Google Images: BMP, GIF, JPEG, PNG, WebP, SVG and AVIF.
Image sitemaps help Google find images it might not discover otherwise, for example ones loaded with JavaScript. The tag that matters is image:loc; Google has removed the caption, title, geo_location and license tags from its documentation.
Licence and creator: IPTC metadata in the file or structured data can earn a photo the Licensable badge in Google Images. Google does not guarantee that it will appear.

In a shop these rules apply to every product page. The alt text describes the product and a feature, for example "black 350 ml ceramic mug on a white background", and the file name contains the product name. The main photo should be in a supported format and load without delay.

Typical mistakes are alt text that repeats the file name, the same alt on every image in a gallery, and important details such as product dimensions shown only inside the image rather than in the page text. On marketplaces, keep overlays off the photo altogether: eBay UK warns that badges, logos, copyright notices or watermarks on listing images can affect a listing's placement in search results.

Frequently asked questions

How do I check the EXIF data of a photo?

On Windows, right-click the file, choose Properties and open the Details tab. On a Mac, use Get Info in Finder or the Inspector in Preview, and on a phone swipe up on the photo in your gallery. ExifTool lists every field, including manufacturer data.

How do I remove location and EXIF data from a photo?

On Windows, the Details tab in Properties has a link called Remove Properties and Personal Information. ExifTool is more thorough: exiftool -all= photo.jpg deletes the metadata. Check the file again afterwards, because not every format is cleaned completely.

How do I convert a HEIC photo to JPG?

On an iPhone go to Settings, Camera, Formats and choose Most Compatible, and new photos will be saved as JPG. On a Mac, open existing files in Preview and export them as JPEG. An iPhone may also convert photos itself when you import them over USB.

Is HEIC better than JPG?

HEIC files are roughly half the size at similar quality and support transparency, which makes them ideal for storage on a phone. JPG opens in every program and browser, so for your shop, marketplaces and sending files to clients JPG or WebP is the better choice.

Is HEIF an Apple format?

No. HEIF was developed by MPEG and is defined in ISO/IEC 23008-12. Apple was the first major company to adopt it, in iOS 11 in 2017, using the HEIC variant with the HEVC codec, which is covered by patents.

Is PNG better quality than JPG?

PNG stores the image losslessly, so there are no compression artefacts, but a photo saved as PNG is much heavier. For product photos on a website a well-exported JPG, WebP or AVIF is enough. Choose PNG for transparent backgrounds, logos and graphics with text.

How can I reduce the file size of a photo without losing quality?

First reduce the pixel dimensions to the size at which the photo is displayed, then save it as WebP or AVIF with moderate compression and compare at 100% zoom. Only lossless compression is truly loss-free, but with photos it saves far less.

Does an image file name matter for SEO?

Yes. Google recommends short, descriptive file names, such as black-ceramic-mug.jpg instead of IMG_2011.jpg. The file name is one of several signals alongside alt text, captions and the text around the image, so it works best together with them.