Cloudinary Blog

How to control the zoom level with automatic face detection based image cropping

Control the zoom level with automatic image cropping

Many websites now offer their users the ability to upload images and profile pictures, making it a challenge for web designers to maintain a certain graphic design and style when subsequently displaying these images. The profile pictures may need to be smartly cropped to focus on the faces, with some sites that prefer close-ups of faces and others that prefer including more background when displaying images of people.

Cloudinary's automatic Face Detection feature is an extremely useful method for identifying the face(s) in uploaded images and then making it a simple matter to intelligently crop, position and resize the picture accordingly. However, the resulting image is cropped at a default zoom level, so to be able to control how much of the original image surrounding the face to keep, Cloudinary has introduced the Zoom parameter that can be added to dynamic image delivery URLs with on-the-fly cloud-based manipulation.

The zoom parameter (z for URLs) accepts a decimal value that sets the new zoom level as a multiple of the default zoom setting: a value less than 1.0 zooms out and a value greater than 1.0 zooms in. For example, z_0.5 halves the default zoom to 50% and zooms out to include more of the background around the face, while z_2.0 doubles the default zoom to 200% and zooms in to include less of the background around the face. The zoom parameter works together with either the crop or thumb cropping modes while setting the gravity parameter to focus on either a single face (g_face), multiple faces (g_faces) or custom coordinates (g_custom) manually defined by the user when uploading the image. Here are a few examples to show how to use the zoom parameter:

Single face thumbnail

The following example demonstrates how the zoom parameter works together with the thumb cropping mode. This mode generates a thumbnail of an image with the exact given width and height dimensions, while identifying the face and making it the center of the image.

The original proportions are retained, but the image might be scaled to fit in the given dimensions. The zoom parameter will now determine how much to scale the face within the given width and height, with a zoom value less than 1.0 shrinking the face, and a zoom value greater than 1.0 enlarging the face within the image.

Original photo

The following URL dynamically generates a 200x200 thumbnail focusing on the face in the image shown above with the default zoom level.

Ruby:
cl_image_tag("lady.jpg", :gravity=>"face", :width=>200, :height=>200, :crop=>"thumb")
PHP:
cl_image_tag("lady.jpg", array("gravity"=>"face", "width"=>200, "height"=>200, "crop"=>"thumb"))
Python:
CloudinaryImage("lady.jpg").image(gravity="face", width=200, height=200, crop="thumb")
Node.js:
cloudinary.image("lady.jpg", {gravity: "face", width: 200, height: 200, crop: "thumb"})
Java:
cloudinary.url().transformation(new Transformation().gravity("face").width(200).height(200).crop("thumb")).imageTag("lady.jpg");
JS:
cloudinary.imageTag('lady.jpg', {gravity: "face", width: 200, height: 200, crop: "thumb"}).toHtml();
jQuery:
$.cloudinary.image("lady.jpg", {gravity: "face", width: 200, height: 200, crop: "thumb"})
React:
<Image publicId="lady.jpg" >
  <Transformation gravity="face" width="200" height="200" crop="thumb" />
</Image>
Angular:
<cl-image public-id="lady.jpg" >
  <cl-transformation gravity="face" width="200" height="200" crop="thumb">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("face").Width(200).Height(200).Crop("thumb")).BuildImageTag("lady.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("face").width(200).height(200).crop("thumb")).generate("lady.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("face").setWidth(200).setHeight(200).setCrop("thumb")).generate("lady.jpg")!, cloudinary: cloudinary)
200x200 thumbnail with default zoom photo

To include more of the background around the face and decrease the relative size of the face within the image, we can decrease the zoom level to 70% of the default by setting the zoom parameter to 0.7:

Ruby:
cl_image_tag("lady.jpg", :gravity=>"face", :zoom=>0.7, :width=>200, :height=>200, :crop=>"thumb")
PHP:
cl_image_tag("lady.jpg", array("gravity"=>"face", "zoom"=>0.7, "width"=>200, "height"=>200, "crop"=>"thumb"))
Python:
CloudinaryImage("lady.jpg").image(gravity="face", zoom=0.7, width=200, height=200, crop="thumb")
Node.js:
cloudinary.image("lady.jpg", {gravity: "face", zoom: "0.7", width: 200, height: 200, crop: "thumb"})
Java:
cloudinary.url().transformation(new Transformation().gravity("face").zoom(0.7).width(200).height(200).crop("thumb")).imageTag("lady.jpg");
JS:
cloudinary.imageTag('lady.jpg', {gravity: "face", zoom: "0.7", width: 200, height: 200, crop: "thumb"}).toHtml();
jQuery:
$.cloudinary.image("lady.jpg", {gravity: "face", zoom: "0.7", width: 200, height: 200, crop: "thumb"})
React:
<Image publicId="lady.jpg" >
  <Transformation gravity="face" zoom="0.7" width="200" height="200" crop="thumb" />
</Image>
Angular:
<cl-image public-id="lady.jpg" >
  <cl-transformation gravity="face" zoom="0.7" width="200" height="200" crop="thumb">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("face").Zoom(0.7).Width(200).Height(200).Crop("thumb")).BuildImageTag("lady.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("face").zoom(0.7).width(200).height(200).crop("thumb")).generate("lady.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("face").setZoom(0.7).setWidth(200).setHeight(200).setCrop("thumb")).generate("lady.jpg")!, cloudinary: cloudinary)
200x200 thumbnail with 70% zoom photo

To include less of the background around the face and increase the relative size of the face within the image, we can increase the zoom level to 130% of the default by setting the zoom parameter to 1.3:

Ruby:
cl_image_tag("lady.jpg", :gravity=>"face", :zoom=>1.3, :width=>200, :height=>200, :crop=>"thumb")
PHP:
cl_image_tag("lady.jpg", array("gravity"=>"face", "zoom"=>1.3, "width"=>200, "height"=>200, "crop"=>"thumb"))
Python:
CloudinaryImage("lady.jpg").image(gravity="face", zoom=1.3, width=200, height=200, crop="thumb")
Node.js:
cloudinary.image("lady.jpg", {gravity: "face", zoom: "1.3", width: 200, height: 200, crop: "thumb"})
Java:
cloudinary.url().transformation(new Transformation().gravity("face").zoom(1.3).width(200).height(200).crop("thumb")).imageTag("lady.jpg");
JS:
cloudinary.imageTag('lady.jpg', {gravity: "face", zoom: "1.3", width: 200, height: 200, crop: "thumb"}).toHtml();
jQuery:
$.cloudinary.image("lady.jpg", {gravity: "face", zoom: "1.3", width: 200, height: 200, crop: "thumb"})
React:
<Image publicId="lady.jpg" >
  <Transformation gravity="face" zoom="1.3" width="200" height="200" crop="thumb" />
</Image>
Angular:
<cl-image public-id="lady.jpg" >
  <cl-transformation gravity="face" zoom="1.3" width="200" height="200" crop="thumb">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("face").Zoom(1.3).Width(200).Height(200).Crop("thumb")).BuildImageTag("lady.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("face").zoom(1.3).width(200).height(200).crop("thumb")).generate("lady.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("face").setZoom(1.3).setWidth(200).setHeight(200).setCrop("thumb")).generate("lady.jpg")!, cloudinary: cloudinary)
200x200 thumbnail with 130% zoom photo

Multiple faces cropping

The following example demonstrates how the zoom parameter works together with the crop mode. This mode is used to extract a section out of the original image, while retaining the size of the graphics, and together with the gravity parameter set to faces, cropping will center the derived image on the detected faces in the image. The zoom parameter will now determine the dimensions of the extracted image, resulting in a bigger image when the zoom value is less than 1.0, or a smaller image when the zoom value is greater than 1.0.

Original photo

The following URL dynamically crops the image shown above to only display the detected faces at the default zoom level:

Ruby:
cl_image_tag("young_couple.jpg", :gravity=>"faces", :crop=>"crop")
PHP:
cl_image_tag("young_couple.jpg", array("gravity"=>"faces", "crop"=>"crop"))
Python:
CloudinaryImage("young_couple.jpg").image(gravity="faces", crop="crop")
Node.js:
cloudinary.image("young_couple.jpg", {gravity: "faces", crop: "crop"})
Java:
cloudinary.url().transformation(new Transformation().gravity("faces").crop("crop")).imageTag("young_couple.jpg");
JS:
cloudinary.imageTag('young_couple.jpg', {gravity: "faces", crop: "crop"}).toHtml();
jQuery:
$.cloudinary.image("young_couple.jpg", {gravity: "faces", crop: "crop"})
React:
<Image publicId="young_couple.jpg" >
  <Transformation gravity="faces" crop="crop" />
</Image>
Angular:
<cl-image public-id="young_couple.jpg" >
  <cl-transformation gravity="faces" crop="crop">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("faces").Crop("crop")).BuildImageTag("young_couple.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("faces").crop("crop")).generate("young_couple.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("faces").setCrop("crop")).generate("young_couple.jpg")!, cloudinary: cloudinary)
Cropped to detected faces with default zoom

To include more of the background around the faces and increase the size of the resulting image, we can decrease the zoom level to 75% of the default by setting the zoom parameter to 0.75:

Ruby:
cl_image_tag("young_couple.jpg", :gravity=>"faces", :zoom=>0.75, :crop=>"crop")
PHP:
cl_image_tag("young_couple.jpg", array("gravity"=>"faces", "zoom"=>0.75, "crop"=>"crop"))
Python:
CloudinaryImage("young_couple.jpg").image(gravity="faces", zoom=0.75, crop="crop")
Node.js:
cloudinary.image("young_couple.jpg", {gravity: "faces", zoom: "0.75", crop: "crop"})
Java:
cloudinary.url().transformation(new Transformation().gravity("faces").zoom(0.75).crop("crop")).imageTag("young_couple.jpg");
JS:
cloudinary.imageTag('young_couple.jpg', {gravity: "faces", zoom: "0.75", crop: "crop"}).toHtml();
jQuery:
$.cloudinary.image("young_couple.jpg", {gravity: "faces", zoom: "0.75", crop: "crop"})
React:
<Image publicId="young_couple.jpg" >
  <Transformation gravity="faces" zoom="0.75" crop="crop" />
</Image>
Angular:
<cl-image public-id="young_couple.jpg" >
  <cl-transformation gravity="faces" zoom="0.75" crop="crop">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("faces").Zoom(0.75).Crop("crop")).BuildImageTag("young_couple.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("faces").zoom(0.75).crop("crop")).generate("young_couple.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("faces").setZoom(0.75).setCrop("crop")).generate("young_couple.jpg")!, cloudinary: cloudinary)
Cropped to detected faces with 75% zoom

To include less of the background around the faces and decrease the size of the resulting image, we can increase the zoom level to 150% of the default by setting the zoom parameter to 1.5:

Ruby:
cl_image_tag("young_couple.jpg", :gravity=>"faces", :zoom=>1.5, :crop=>"crop")
PHP:
cl_image_tag("young_couple.jpg", array("gravity"=>"faces", "zoom"=>1.5, "crop"=>"crop"))
Python:
CloudinaryImage("young_couple.jpg").image(gravity="faces", zoom=1.5, crop="crop")
Node.js:
cloudinary.image("young_couple.jpg", {gravity: "faces", zoom: "1.5", crop: "crop"})
Java:
cloudinary.url().transformation(new Transformation().gravity("faces").zoom(1.5).crop("crop")).imageTag("young_couple.jpg");
JS:
cloudinary.imageTag('young_couple.jpg', {gravity: "faces", zoom: "1.5", crop: "crop"}).toHtml();
jQuery:
$.cloudinary.image("young_couple.jpg", {gravity: "faces", zoom: "1.5", crop: "crop"})
React:
<Image publicId="young_couple.jpg" >
  <Transformation gravity="faces" zoom="1.5" crop="crop" />
</Image>
Angular:
<cl-image public-id="young_couple.jpg" >
  <cl-transformation gravity="faces" zoom="1.5" crop="crop">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation().Gravity("faces").Zoom(1.5).Crop("crop")).BuildImageTag("young_couple.jpg")
Android:
MediaManager.get().url().transformation(new Transformation().gravity("faces").zoom(1.5).crop("crop")).generate("young_couple.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation().setGravity("faces").setZoom(1.5).setCrop("crop")).generate("young_couple.jpg")!, cloudinary: cloudinary)
Cropped to detected faces with 150% zoom

Single face cropping with multiple face thumbnail overlay

The following URL dynamically crops the lady.jpg image to only display the face at a zoom level of 90% and with rounded corners, then overlays a circular 150x150 thumbnail of the young_couple.jpg image with a zoom level of 75%. The overlay is also adjusted to display 10 pixels away from the north east corner by using the fl_layer_apply parameter, which allows multiple transformations to be applied on the overlay (see the blog post on manipulating overlays for more info).

Ruby:
cl_image_tag("lady.jpg", :transformation=>[
  {:gravity=>"face", :radius=>50, :zoom=>0.9, :crop=>"crop"},
  {:overlay=>"young_couple", :width=>150, :height=>150, :radius=>"max", :gravity=>"faces", :zoom=>0.75, :crop=>"thumb"},
  {:flags=>"layer_apply", :gravity=>"north_east", :y=>10, :x=>10}
  ])
PHP:
cl_image_tag("lady.jpg", array("transformation"=>array(
  array("gravity"=>"face", "radius"=>50, "zoom"=>0.9, "crop"=>"crop"),
  array("overlay"=>"young_couple", "width"=>150, "height"=>150, "radius"=>"max", "gravity"=>"faces", "zoom"=>0.75, "crop"=>"thumb"),
  array("flags"=>"layer_apply", "gravity"=>"north_east", "y"=>10, "x"=>10)
  )))
Python:
CloudinaryImage("lady.jpg").image(transformation=[
  {"gravity": "face", "radius": 50, "zoom": 0.9, "crop": "crop"},
  {"overlay": "young_couple", "width": 150, "height": 150, "radius": "max", "gravity": "faces", "zoom": 0.75, "crop": "thumb"},
  {"flags": "layer_apply", "gravity": "north_east", "y": 10, "x": 10}
  ])
Node.js:
cloudinary.image("lady.jpg", {transformation: [
  {gravity: "face", radius: 50, zoom: "0.9", crop: "crop"},
  {overlay: "young_couple", width: 150, height: 150, radius: "max", gravity: "faces", zoom: "0.75", crop: "thumb"},
  {flags: "layer_apply", gravity: "north_east", y: 10, x: 10}
  ]})
Java:
cloudinary.url().transformation(new Transformation()
  .gravity("face").radius(50).zoom(0.9).crop("crop").chain()
  .overlay("young_couple").width(150).height(150).radius("max").gravity("faces").zoom(0.75).crop("thumb").chain()
  .flags("layer_apply").gravity("north_east").y(10).x(10)).imageTag("lady.jpg");
JS:
cloudinary.imageTag('lady.jpg', {transformation: [
  {gravity: "face", radius: 50, zoom: "0.9", crop: "crop"},
  {overlay: "young_couple", width: 150, height: 150, radius: "max", gravity: "faces", zoom: "0.75", crop: "thumb"},
  {flags: "layer_apply", gravity: "north_east", y: 10, x: 10}
  ]}).toHtml();
jQuery:
$.cloudinary.image("lady.jpg", {transformation: [
  {gravity: "face", radius: 50, zoom: "0.9", crop: "crop"},
  {overlay: "young_couple", width: 150, height: 150, radius: "max", gravity: "faces", zoom: "0.75", crop: "thumb"},
  {flags: "layer_apply", gravity: "north_east", y: 10, x: 10}
  ]})
React:
<Image publicId="lady.jpg" >
  <Transformation gravity="face" radius="50" zoom="0.9" crop="crop" />
  <Transformation overlay="young_couple" width="150" height="150" radius="max" gravity="faces" zoom="0.75" crop="thumb" />
  <Transformation flags="layer_apply" gravity="north_east" y="10" x="10" />
</Image>
Angular:
<cl-image public-id="lady.jpg" >
  <cl-transformation gravity="face" radius="50" zoom="0.9" crop="crop">
  </cl-transformation>
  <cl-transformation overlay="young_couple" width="150" height="150" radius="max" gravity="faces" zoom="0.75" crop="thumb">
  </cl-transformation>
  <cl-transformation flags="layer_apply" gravity="north_east" y="10" x="10">
  </cl-transformation>
</cl-image>
.Net:
cloudinary.Api.UrlImgUp.Transform(new Transformation()
  .Gravity("face").Radius(50).Zoom(0.9).Crop("crop").Chain()
  .Overlay("young_couple").Width(150).Height(150).Radius("max").Gravity("faces").Zoom(0.75).Crop("thumb").Chain()
  .Flags("layer_apply").Gravity("north_east").Y(10).X(10)).BuildImageTag("lady.jpg")
Android:
MediaManager.get().url().transformation(new Transformation()
  .gravity("face").radius(50).zoom(0.9).crop("crop").chain()
  .overlay("young_couple").width(150).height(150).radius("max").gravity("faces").zoom(0.75).crop("thumb").chain()
  .flags("layer_apply").gravity("north_east").y(10).x(10)).generate("lady.jpg");
iOS:
imageView.cldSetImage(cloudinary.createUrl().setTransformation(CLDTransformation()
  .setGravity("face").setRadius(50).setZoom(0.9).setCrop("crop").chain()
  .setOverlay("young_couple").setWidth(150).setHeight(150).setRadius("max").setGravity("faces").setZoom(0.75).setCrop("thumb").chain()
  .setFlags("layer_apply").setGravity("north_east").setY(10).setX(10)).generate("lady.jpg")!, cloudinary: cloudinary)
Cropped to the detected face with 90% zoom and rounded corners, with 150x150 circular thumbnail overlay at 75% zoom and 10 pixels away from the north east corner

As shown in the example above, any of Cloudinary's image transformations can also be applied to the delivered image.

Summary

When automatically cropping images to focus on the detected face(s), the zoom parameter is used to control how much of the original image surrounding the face to keep, and is a powerful method to modify and normalize user generated content to match the graphic design and style of your site.

The new Zoom feature is available to all our free and paid plans. If you don't have a Cloudinary account, you are welcome to sign up to our free account and try it out.

Recent Blog Posts

How to Make Boomerang Video Effect With Cloudinary

When you see the term boomerang, what is the first thing that comes to mind?

A thrown tool made of wood that returns to its thrower? Another definition is reversal, logically portraying the aim of the tool itself. Based on this definition, the term boomerang videos” came into play to depict videos that loop back and forth.

Read more
Shortening the Development Cycle of Media-Related apps with Cloudinary

Currently, the Android platform boasts the highest demand for mobile solutions, as evidenced by Google’s announcement in 2017 that there were two billion monthly active Android devices, a number that is likely to increase in the years ahead. For app developers like you, now is the right time to build and release solutions for Android. you might have also noticed that a higher percentage of apps being developed nowadays are filled with visual media: images and videos.

Read more
Build Your Own Image Storyboard Android App

Globally, approximately two billion people now own smartphones, which also feature cameras capable of capturing photos and videos of a tonal richness and quality unimaginable even five years ago. Until recently, those cameras behaved mostly as optical sensors, catching light that determines the resulting image's pixels. The next generation of cameras, however, can blend hardware and computer-vision algorithms that apply to an image's semantic content, spawning creative mobile photo and video apps.

Read more
Cloudinary Delivers Simplified Image Management Workflow for Fairfax Media's Digital Transformation

Fairfax Media Limited [ASX:FXJ] is one of the largest media companies in Australia and New Zealand that engages audiences and communities via print and digital media. It includes recognizable mastheads including The Australian Financial Review, The Sydney Morning Herald and The Age. Fairfax Media operates numerous news and information websites, as well as tablet and smartphone apps, for online news sites.

Read more
Bleacher Report Scores with Real-Time Video Highlights Delivered by Cloudinary

Bleacher Report is a global digital destination for sports fans, creating and collaborating on content at the intersection of sports and culture. Owned by Turner, a division of Time Warner, Bleacher Report's website and social channels focus on sports culture for the next generation of fans. Bleacher Report also has a five-star mobile app and popular email newsletters, which are part of the company’s strategy for instantly delivering in-depth articles, results and video highlights personalized for users’ favorite teams, players and leagues.

Read more