Convert a Bitmap mode image to Grayscale mode

Last updated on Oct 27, 2025

Learn how to convert a Bitmap mode image to Grayscale mode in Adobe Photoshop to unlock more editing options and generate shades of gray from black-and-white artwork.

Grayscale mode expands a Bitmap image into shades of gray, making it easier to edit. Keep in mind that edits made in Grayscale may not appear the same if you later convert back to Bitmap. For example, a pixel changed to a light gray value in Grayscale will convert back to white in Bitmap if its brightness is above 128.

Before you begin

Save a copy of the Bitmap image before converting, as converting back may not preserve edits.

Open your Bitmap mode image.

Select Image > Mode > Grayscale from the menu bar.

In the Size Ratio dialog box, enter a value between 1 and 16.

  • The size ratio determines how pixels are averaged when scaling down the Bitmap image.
  • For example, entering 2 reduces the image by 50% by averaging two Bitmap pixels into one Grayscale pixel.
  • Higher values generate smoother shades of gray from a 1-bit scanned image.