Convert PDF and photo files to text

Prepare the file
These tips will give you the best results:

Format: You can convert .JPEG, .PNG, .GIF, or PDF (multipage documents) files.
File size: The file should be 2 MB or less.
Resolution: Text should be at least 10 pixels high.
Orientation: Documents must be right-side up. If your image is facing the wrong way, rotate it before uploading it to Google Drive.
Languages: Google Drive will detect the language of the document.
Font and character set: For best results, use common fonts such as Arial or Times New Roman.
Image quality: Sharp images with even lighting and clear contrasts work best.

via Convert PDF and photo files to text – Computer – Google Drive Help