Web graphics at different resolutions

Testing file sizes of images saved at 72 dpi vs. 600 dpi. GIFs and PNGs are approximately the same file size regardless of the image resolution. Based on discussions at MetaFilter and TalkGraphics.com.

Photoshop’s Save for Web reduced the resolution of all of the images to 72 DPI regardless of the initial setting; using Save As retained the initial DPI settings.

72 DPI GIF
GIF
72
303
600 DPI GIF
GIF
600
309
72 DPI JPEG
JPEG
72
537
600 DPI JPEG
JPEG
600
2,284
27 DPI PNG
PNG
72
1,880
600 DPI PNG
PNG
600
1,880

Methodology

  1. In Photoshop 6.0.1’s New dialog box, set height and width to 20 pixels and resolution to either 72 or 600 dpi (RGB Mode)
  2. Use the paint bucket to fill the entire image with a web-safe color
  3. In Photoshop’s Save As dialog box, save as GIF, JPEG, or PNG, accepting default settings
  4. Repeat steps 1–3 for each image