Why do gradients show visible bands after I save an image?

The visible stripes are commonly called banding: a gradual color change appears as separate steps. Limited color information and heavy compression can contribute to it. [S1] Saving can expose or worsen the problem, but first check whether the bands are actually in the saved file rather than relying only on the editor’s preview.

Try this comparison:

1. Reopen the exported file in your editor or view it in another image viewer.
2. Compare it with the working image at the same approximate size and zoom.
3. Export a second test copy with less compression, if the app provides that control.

If the saved copy shows stronger bands than the working image, export settings may be one contributor. If both show them, the gradient may already have limited color information. This comparison is a troubleshooting method, not proof of one specific cause.

Keep the source project untouched and make a duplicate or a new export for each test. Change one thing at a time so you can tell which version looks better. If the export dialog offers a compression-quality control, test a less-compressed version and compare it with your current file. Heavy compression is a documented possible contributor, but the available guidance does not specify the right format, quality value, or settings for every app. [S1]

If your editor lets you choose color depth, check whether a higher-bit-depth working image is available before applying a banding fix. In Pixelmator Pro on Mac, the guide recommends changing the image to 16 bits per channel before using its Deband feature for best results. [S1] That instruction is specific to that application; it does not establish that other editors have the same command or behave identically.

Work on a duplicate layer or project copy so you can compare the result and keep the unedited version. The Pixelmator Pro for Mac guide says to select a layer and choose Format > Deband; it also provides a before-and-after comparison. It recommends changing the image to 16 bits per channel before Deband for best results. [S1]

A simple test sequence is:

1. Duplicate the project or layer.
2. If appropriate for your workflow, change the image to 16 bits per channel.
3. Select the target layer and choose Format > Deband.
4. Inspect the before-and-after comparison, especially where the gradient is smoothest.
5. Export a test and reopen it to check the saved result.

These steps are for Pixelmator Pro on Mac. The guide does not establish that debanding restores all lost detail or removes every visible band.

Use the same gradient area and viewing conditions for each comparison. For example, if the working image looks smooth but the first export has visible steps, save a second test with less compression while leaving other settings unchanged. Compare the reopened file with the first export. If it looks better, you can use those settings for another test; if not, return to the project copy and change one other setting. This is a comparison method, not a promised result.

Record the app, chosen export settings, and which copy you inspected. Judge the reopened file, not just the export dialog’s preview. If banding remains, consider whether it was present in the working image and whether your editor provides a suitable debanding option. Avoid overwriting the original until you have checked the final saved file.