Ponga Help

What are the limits of face detection?

Computer Vision technologies have transformed face detection functions, but they have limits.

Ponga can detect faces at a wide variety of poses, facial expressions, age ranges, rotations, lighting conditions, and sizes. The results can be magical, but they aren't magic.

Here are some things to keep in mind that affect Ponga's ability to match faces and names.

Age Affects our Faces

As anyone whose crossed a milestone birthday can tell you, our faces change with age. Generally, the software uses patterns to match different images of one person and conclude they are the same person. That works to the extent that a person's visage remains roughly the same.

Large age differences can be tricky. In childhood, it's harder to spot the character lines we develop as we age. Even a mother can be confused by baby pictures of her own children. Computers can be confused too. Similarly, near end of life, when changes to the jaw from dental work or injury might substantially change facial geometry, automated detection can be less accurate.

On the whole, the geometry of our facial features tends to be pretty consistent  through the middle of life from adolescence to our golden years.

TIP: If you have a number of pictures where file names, labels or other elements make naming easy, add these pictures first.

You may have to add the names in the Gallery, but auto-complete and the Quicklook features will make it easy. Each new portrait you name for a given person becomes a teaching aid to give Ponga the confidence to add names for you, effectively recognizing new pictures you add.

Resolution and Sharpness Matter Too!

The minimum size and resolution for face detection is 40 by 40 pixels, at an HD resolution of 1920 x 1080. For context, 40x40 pixels is about the size of the maid Gwen's face in this HD image of the lineup from Downton Abbey.

In this color photo, the color itself plus the remarkable sharpness of a professional composite image ensure a very clear and recognizable image for each person. The pixel range is necessary, but not sufficient.

If you add a photo of a large gathering of people and are disappointed that you're not able to name everyone, don't despair. Here are a few tricks.

  1. Find someone with the original print or negative. A fresh, high-resolution scan of the image may turn up additional resolution. Local scanning professionals can be helpful with this. Be sure to share with them that you're using our Ponga.com service and that we can support images of any file size as long as they're in jpg, png, or tif format.
  2. Does someone else in your family have the original, or a higher-resolution scan? In days before digital cameras, inherited photos were often shared among descendants by splitting the collection. Don't be shy about asking family or searching on genealogy sites like Ancestry or FamilySearch.
  3. Can you find another copy of the original using Google Image Search or even TinEye? These nifty tools use advanced technologies to protect copyright holders, but they're also free services you can use to see if you can find another copy of your photo elsewhere in the world.

Keep Resolution in Mind if You Design Digital Scrapbook Layouts

Arranging multiple pictures in the style of a digital scrapbook can recreate the storytelling experience of the printed page, but don't skimp on file size and resolution. It's the high resolution that can make each detail of a face visible to Ponga. You want to preserve that.

Let's say you have an "HD" sized image of 1920x1080 pixels and you want to combine it with another similarly sized "HD" image on a page of the same aspect ratio. The logical thing to do is to downsize the two images so they fit on the new page. That's fine from a layout perspective, but it reduces the resolution of the faces included in the two images. The better thing to do is to make sure your assembly page is larger so that resolution isn't compromised.

Have questions? Feel free to reach out.

Image Credit: Downton Abbey Wiki on Fandom.

(In case you wondered, yes, the character of Gwen noted in the Downton Abbey image is played by actress Rose Leslie, who was also in Game of Thrones and in real life married to Kit Harington, the actor who plays Jon Snow. 🤔 💭 Gosh, THAT would be fun to represent and explore in Ponga, huh? )

Last updated:
February 26, 2023
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