Using an image resizer can affect image quality depending on how much the photo is changed. Reducing the dimensions of a large, high-resolution image usually maintains good visual quality. However, enlarging a small image too much can make it appear blurry or pixelated. For better results, start with the highest-quality original available, maintain the aspect ratio, and avoid repeatedly resizing the same file. Always preview the resized image before using it on a website or sharing it online.