Here is what Google says in its help page:
Optical Character Recognition (OCR) lets you convert images with text into text documents using automated computer algorithms. Images can be processed individually (.jpg, .png, and .gif files) or in multi-page PDF documents (.pdf). These are some of the types of files suitable for OCR:To access this service, follow these steps:
- Image or PDF files obtained using flatbed scanners
- Photos taken with digital cameras or mobile phones
- Sign in to Google Drive.
- Upload your scanned image or PDF.
- When the file is done uploading, right-click on its icon and choose Open with... > Google Docs.
- Wait a few seconds (longer, if you have a bigger document) as Google Drive processes the file. Your document will open in Google Docs with the converted text inside.
Note: There are limits, so please read the Google Drive OCS help page.