Erase versus ignore misidentified unconfirmed faces.

[jln]

A photo with bystanders will not recognize all faces as faces, but sometimes it gives an unconfirmed identification or no identification. Occasionally it will recognize something that is not a face as a face and also give either an unconfirmed identification or no confirmation.

I am unsure whether it is better to just erase the face rectangle in these cases or mark them "ignore"? What is the difference in the later way iMatch would treat these photos?

[Mario]

A photo with bystanders will not recognize all faces as faces, but sometimes it gives an unconfirmed identification or no identification. Occasionally it will recognize something that is not a face as a face and also give either an unconfirmed identification or no confirmation.

This is all perfectly normal. No AI is perfect. We are.

I am unsure whether it is better to just erase the face rectangle in these cases or mark them "ignore"?

I cannot answer this better as it is already answered in the IMatch Help System:

4. Ignored

[jln]

I realize no AI is perfect. When you say "we are," I assume you are referring to yourself. I am far from perfect.

The issue that isn't clear to me from the help is that if I simply delete the face recognition rectangle, is there a chance that iMatch will (incorrectly) re-recognize that later? The only difference I see from the help is that "ignore" means iMatch will know the image still has a face. So if a confirmed face is in the same image, there is no difference, since an image with a confirmed face will let iMatch know there is a face? 

[sybersitizen]

The issue that isn't clear to me from the help is that if I simply delete the face recognition rectangle, is there a chance that iMatch will (incorrectly) re-recognize that later?

Only if you run face detection again on that same file. Would you ever do that?

The only difference I see from the help is that "ignore" means iMatch will know the image still has a face. So if a confirmed face is in the same image, there is no difference, since an image with a confirmed face will let iMatch know there is a face?

I think that's mostly correct, though it could change the total face count for that image. Maybe it would help to read this older thread where I had some similar questions:

https://www.photools.com/community/index.php/topic,14470.msg101643.html#msg101643

For cases where there are 'unknown' faces that I might want to add to my list of officially recognized people in the future, I created a person named 'A Face to Review' and I assign those faces to that person. I make them Untrained but Confirmed. Seems to work okay so far, but the list is very short.

[Mario]

If you don't want to keep the face, you delete it. If you use features like grouping images based on how many faces they contain and in which layout ("group of people"), even ignored faces count.

If your image has one confirmed face, but there are several other persons in the background you don't know, deleting these faces will put the image into the "One Person" group, losing the information that this image shows one known person but actually a group pf persons. If this is irrelevant for you, you can delete the faces, else you ignore them.

IMatch does not run face recognition automatically on images which already have faces. Press <F6> in the Viewer for a file which already has faces to see. When you run face recognition from the File Window and you un-check the option to skip files which already have faces, IMatch removes all faces from the selected images and then re-runs face recognition. This will bring back deleted faces.