Last updated: July 03, 2013

 

User's Guide

 

  1. Introduction
  2. Using faceBlock

    a) Opening pictures
    b) Removing pictures from the list
    c) Face detection
    d) Blocking faces
    e) Export settings
    f) Exporting face images
    g) Exporting entire pictures

  3. Preferences

    a) General settings
    b) Folders

  4. FAQ

  5. Credit: Some of the pictures used here come from PDPhoto.

 

 

1. Introduction

faceBlock is a desktop application that utilizes OSX's Core Image to detect faces on pictures so that they can be isolated as separated images or entire pictures can be exported with faces filtered.  The screenshot below is an example where detected faces are filtered with CIPixellate - the selected area consists of pixels that are larger than original ones.

 

Mac software faceBlock

Screenshot 1-01

 

The user interface of the application is simple.  There are several toolbar buttons at the top.  Click on the leftmost toolbar button to open Preferences to configure default settings.  The second toolbar button from the left end is used to open and select pictures to work with.  Click on the third one to open a drop box.  The other two toolbar buttons are used to export images.  When the user selects and opens one or more pictures, they will be listed with their file names and dimensions.

Notice that there is a switch control right below the file list.  When you click on the Detection tab, the application will display the entire selected picture with faces that are detected.  When you click on the Face block tab, the controls inside the Settings group box will be applicable so that they can block detected faces.

 

2. Using faceBlock

a) Opening pictures

The first thing you need to do when you launch faceBlock is to select and open pictures.  So let's click on the Open Picture toolbar button.  (Or choose Open Picture under File.)  Clicking on it, you will be prompted to select pictures.  (See Screenshot 2-01.)  faceBlock lets you select any type of files, even text files, so that it can prevent itself from crashing when one of the image files that the user has selected is an invalid one.  Meanwhile, the image types that are currently supported are BMP, GIF, JPEG, JPEG 2000, PDF, PNG, TIFF.

 

Mac software faceBlock

Screenshot 2-01

Mac software faceBlock

Screenshot 2-02

 

Taking a close look at Screenshot 2-01, notice that the application will first point you to the Documents folder.  That's the default path.  If you want to set a different default open-folder path, click on the Preferences toolbar button (leftmost) and navigate to Folders.  Then choose 'Others...' to select an alternative open-folder path.  (See Screenshot 2-02.)

When you are prompted to select pictures, literally, you can select not just one but any number of image files.  (See Screenshot 2-03.)  If necessary, hold down the Shift key while selecting multiple files.

 

Mac software faceBlock

Screenshot 2-03

Mac software faceBlock

Screenshot 2-04

 

If you have quick access to pictures that you want to use, you can use a drop box to read them instead of using the open-file dialog and navigating to the ulitimate folder.  Click on the third toolbar button with a drop mark to open the image drop box.  Then just and drop one or more picture files.  (See Screenshot 2-04.)

 

b) Removing pictures from the list

Next, let's see how we can remove pictures that we no longer need from the list.  If you want to remove individual pictures, first, select one to remove in the list.  Then choose Remove Picture under Picture.  (See Screenshot 2-05.)  You can also right-button-click on the file name in the list and choose the same command.  When you attempt to remove the selected picture, you will be prompted for confirmation.  (See Screenshot 2-06.)  Click on Remove to proceed.

 

Mac software faceBlock

Screenshot 2-05

Mac software faceBlock

Screenshot 2-06

 

Similarly, if you have more than one picture in the list, you can choose Remove All Pictures to remove them all.  And you will be prompted for confirmation.

 

c) Face detection

The switch control right below the file list lets you select a preview mode.  Whenever you start up the application, it's set to the Detection mode.  This mode lets you see how the application detects faces - more precisely which face is detected.

While you are under the Detection mode, select any of the pictures in the list.  And the Preview window will open up.  (See Screenshot 2-07, 2-08.)  Each detected face has a somewhat-transparent layer with a white border.  Comparing two pictures, we notice that faceBlock has successfully detected all three faces in the second picture while it has missed one face in the first picture.  So Core Image's API called CIDetector is not perfect.  Although we never know how this API works, we can tell you a rule of thumb as to how you get the best out of this feature.

 

Mac software faceBlock

Screenshot 2-07

Mac software faceBlock

Screenshot 2-08

 

  • A face is defined as a human part (or even animal's part) with two eyes and lips.  Eyes and a mouth must be fairly large.  Eyes must be clearly visible.  Preferably, teeth are visible as well.  faceBlock has failed to detect one of the faces in the first picture probably because the missed face has glasses covering his eyes.  So why doesn't faceBlock recognize the circled face in Screenshot 2-09?  We can only see one of his eyes, can't we?

  • A face must not lie near the edge.  There's a good reason why each preview picture is framed with a white background.  If a face lies near the edge, the application can fail.  Screenshot 2-09 shows a detected small face near the left edge.  The application could fail to recognize this face if the application did not frame the picture.  So make sure that all faces lie away from the edge of the picture.

  • No glasses!  If a face has glasses on it, it is very likely that such face will not be detected unless eyes are visible through them.

 

Mac software faceBlock

Screenshot 2-09

 

 

So do what, next?  Actually, there's no action you can take while you are under the Detection mode.  This mode is designed such that you can find out which face is detected and which face is not before you switch to the other mode.

 

d) Blocking faces

Switching to the Face block mode, you can apply one of five effects (Only one effect can be applied to a picture.) to block detected faces.  When you first open and select pictures, you should see Not selected under the Effect column.  (See Screenshot 2-10.)  In order to apply an effect to the detected faces in a picture, first, select a picture in the list.  Then select an effect under the drop-down menu inside the Settings group box.  (See Screenshot 2-11.)

 

Mac software faceBlock

Screenshot 2-10

Mac software faceBlock

Screenshot 2-11

 

So what are these effects?

 

  • CIDiscBlur: It blurs the detected face with a disc shape.  (See Screenshot 2-11a)
  • CIDotScreen: It covers the detected face with a number of black dots.
  • CICrystallize: It creates large color blocks to cover the detected face.  (See Screenshot 2-11b)
  • CIPixellate: It covers the detected face with tiny colored pixels.
  • CIExposureAdjust: It adjusts the exposure level to make the detected face light-intense (positive) or dark (negative).  (See Screenshot 2-11c)

 

Mac software faceBlock

Screenshot 2-11a

Mac software faceBlock

Screenshot 2-11b


Mac software faceBlock

Screenshot 2-11c

 

 

When you select an effect and then increate its insensity with the Amount slider, faceBlock will first create a layer for each face.  Then the application will apply the selected effect to the face layer by the amount of intensity you've configured.  Whenever you switch effects, the intensity value will be set to 0.  That's because all effects don't share the same pair of minimum and maximum values.  So you won't see changes until you increate the intensity level after selecting a new effect.

There are two more controls we haven't discussed.  The Opacity level simply controls the tranparency level of the face layer.  Even when you intensively apply an effect to faces, if you set the opacity level to 1, then the effect will be nearly non-existent.

By this time, you should have noticed that each detection region is quite small.  The Coverage slider lets expand the size of the face layer to a small degree.  The maximum level is only 10 pixels.  So it's not much.  Screenshot 2-12 compares two cases where the same picture has the coverage area of 0 and 10.  So even when the coverage is extended, we don't see much difference.  There's a good reason why the application won't go beyond 10 pixels.  In the Face detection section, we've discussed how this application can fail to detect faces.  In order to have all faces successfully detected, you need to make sure that they lie away from the edge.  And the application puts each picture in a frame with a white background to make sure that all faces stay away from the edge.  Expanding face coverage requires that the border size also be adjusted.  For now, the border size is inflexible.

 

Mac software faceBlock

Screenshot 2-12

Mac software faceBlock

Screenshot 2-13: CIPxellate

 

Screenshot 2-13 shows an example where CIDotScreen is applied to faces.  When you apply this effect, make sure you keep the amount level low like 4 and 5.  Screenshot 2-14 shows a case where CIPixellate is applied.  CIPixellate is similar to CICrystalize and is easier to use.  If intensity is large with CICrystallize, the face layer will go further away from the original position, which makes the entire picture awkward.

 

Mac software faceBlock

Screenshot 2-14

Mac software faceBlock

Screenshot 2-14a

 

You may now think to yourself that it's kind of time-consuming for you to set a graphic effect to each picture.  If you want to quickly apply the same effect to all pictures, there's a solution.  If you look under the Picture menu, there are five commands under the Apply Effects To All submenu.  (See Screenshot 2-14a.)  If you, for example, choose Apply Effects To All > CIPixellate, you can let faceBlock automatically apply the Pixellate effect to all pictures in the list.  You still have to configure the coverage and other values, respetively, though.

 

 

 

 

 

 

 

 

 

 

 

 

 

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