Shrink photos without losing your originals

For an email, website or advertisement you usually do not need a full camera resolution photo. Create a separate partial copy and choose consciously size, format and quality.

Size and file size are different

The pixel dimensions describe how many pixels a photo has. The file size tells how much storage space the encrypted image uses. A photo with less pixels often gets smaller, but also the file format, content and compression play along. Much fine detail usually requires more data than an even plane.

Pixel dimensions are especially relevant for viewing on a screen. Change only the value for print resolution does not necessarily reduce your image. Choose an appropriate width or height in pixels and keep the aspect ratio, so that faces and objects are not stretched.

Save a separate original

Create an output folder for partial copies, for example next to your photo folder. Give those copies a recognizable name or suffix. Then you can export again from the original when a website asks for different sizes. Re-opening and re-save with loss-making compression can cost extra detail.

First select some representative photos.
Choose a separate output folder.
Set the maximum pixel dimensions while maintaining ratio.
Choose the format that supports the receiver.
Check the output for full display size.

Choose the format for the target

JPEG is widely used for photos, but does not support transparency and uses loss-making compression. PNG is useful when, for example, you want to keep a screenshot with sharp text or transparency, but is often larger for photos. WebP can provide an appropriate partial copy for supported apps. Check the requirements of the website or recipient instead of always choosing the same format.

For some images you can GIMP Use. For a series of photos the batch functions of XnView MP or IrfanView Handy. In batch processing, make sure that the output does not point to your originals.

Remove unwanted metadata intentionally

A photo can contain camera data, timings and sometimes location data. This is useful in your own archive, but not always desired in public sharing. Check which metadata you store and check an output file. The filename can also disclose information, for example the name of a person or an internal project.

Check text, faces and small details

Not just use the number of kilobytes as a quality measure. Look at fine patterns, edges and any text. A photo can be small enough to upload but still unsuitable for purpose. If in doubt, make two trial exports and compare them to the size on which visitors actually see the image.

If the first files are good, apply the same settings to the rest. Save the settings for a next set, but keep the original photos available. This prevents one quick clean-up operation from replacing your only high quality copy.