Immigration Canada requires applicants to supply “Immigration size-specific” photos with Permanent Resident applications. The photo specifications are consistent, regardless of whether you’re filing inland or outside. They're located in Appendix C of the Region Specific Forms for any country, and in Appendix C of the inland application guide. However, the number of photos required varies, and how you are to include the photos in your application package varies depending on whether you file inland or outside.
The info here was compiled from each Region’s Applicant Document Checklist, and from the Applicant’s Guide to completing the application.
Inland Aps: Information is found at the bottom of page 1 of the Document Checklist. Applicants must submit 2 (two) photos of themselves and any dependent children included in their application. Photos must be included in a separate envelope and stapled to the front of form IMM5002. Photos for any dependent children over the age of 18 should be included in another separate envelope and stapled to the front of their own form IMM5002.
Outside Aps: Information on how to process the photos is found on page 15 of the Applicant’s Guide. “On the back of one photo (and only one) in each set, write the name and date of birth of the person appearing in the photo as well as the date the photo was taken. Enclose each set of photos in separate envelopes. Write the family member’s name, date of birth and relationship to you on the corresponding envelope and close the envelope with a paper clip. Photos must not be stapled, scratched, bent or bear any ink marks.” (It doesn’t say what to do with the photo envelopes, so I paperclipped them to Form IMM0008 per the instructions for inland aps above.)
Information on the number of photos to supply varies by country and is in the Applicant Checklist found in each of the Region Specific Forms sections.