Put Round Corners on Pictures

Rose

Put round corners on images, with radii from 0 to half the width of the smallest side of the image. Mask images for see-through effect. Add colorful borders.

This iOS and macOS app applies rounded corners, masks, overlays and borders to images. You can adjust the corner radius from 0 (no rounding) to half the width of the smallest side of the image, enabling you to create anything from subtly rounded edges to perfect circles. Add borders with color.

The app features masking and overlay capabilities. For example by applying a mask with a transparent region in the shape of a star, the app can crop your image to a star-shape, leaving the rest of the image transparent or filled with a customizable solid background color.

Star Mask

The app supports multiple sources for images. You can choose images directly from the Photos library, browse local files, or select files stored in iCloud Drive.

Main View
Pick images with a Photos browser or File Browser
Or specifcally for masks use the mask browser

For convenience, the app includes a collection of built-in masks to help get started quickly.

Masks

Making masks is simple using the Preview app. Simply select the whole image, then cut leaving a fully transparent image. Now add shapes, lines with the markup editor. Save the image to file format that supports transparency - such as PNG or HEIC. Then load the mask from either the file system or Photos.

Another way to create a mask or overlay is to use the image segmentation tool in the certain apps that display photos, such as the Photos app. The feature in the Photos app that allows you to tap on an image to select and copy the foreground without the background is called foreground extraction. Once the foreground is extracted, you can copy it as a separate image with transparent background and save it as a mask or overlay.

Extract to overlay
Tap down on the part of your image that you want to extract.
Select share to save, load it as a mask and select the overlay option in the mask tab.

Features Illustrated

• Rounded Corners (Index)

Round Corners
Load an image with the Photos or File Browser.
Select the corner radius in the Corner tab.

• Crop Square (Index)

Index
Round Corners
Select `Crop Square` in the Image tab.

• Crop Square + Largest Corner Radius (Index)

Fully Round Corners
Select `Crop Square` in the Image tab.
Select 50% corner radius - which is half the length of each side - to make a circle.
Round Corners
Fully Round Corners

• Masking (Index)

Mask
Apply a mask.

• Inverting Masks (Index)

Invert Mask Option
In the mask tab select option to invert the mask.
Transparent pixels become opaque and opaque pixels become transparent.
Apple Background
Image to be masked.
Apple With Transparent Background
Image with a trasnsparent background for mask.
Apple Mask
Apply the mask.
Apple Mask Inverted
Invert the mask.

• Mask as Overlay with Scaling and Translation (Index)

Mask as Overlay
Apply a mask as an overlay.
Use the scale and translation sliders in Mask tab to position it over underlying image.

• Second Mask as Overlay with Scaling and Translation (Index)

Mask as Overlay
Apply a second mask as an overlay.
Use the scale and translation sliders in Mask tab to position it over underlying image.

• Turn Off Mask (Index)

Ignore Mask
In the mask tab select option to ignore the mask to turn it off.

• Mask and Image Opacity (Index)

Checkerboard
Select checkerboard as image.
Apple
Select apple as mask with the overlay option on.
Apple with transparency
In the mask options tab view select an opacity smaller than 1.
The apple becomes transparent.

• Convert Black and White Image to Mask (Index)

Select a photo as the image.
Select a black and white drawing, without any transparency, as a mask.
This black and white image was created solely with the Preview app on the Mac.
Add them to the app.
Select convert to mask in the mask option tab view.
Black pixels become transparent while the white pixels reveal the image.

• Convert Grayscale Image to Mask (Index)

Color or grayscale images can also be used for conversion to a mask. In this case some pixels are only partially transparent, producing a blend.
To see this effect more clearly consider using this stepwise gradient for conversion to a mask.
Again, black pixels become transparent while the white pixels fully reveal the image. But the intermediary grayscale pixels result in partially transparent image pixels.
If you set a blue canvas background it becomes more aparent how the resulting image is partailly transparent.

• Cutout vs. Blend Transparency Mode (Index)

Cutout: Uses transparency as a mask to cut out parts of the image.
Blend: Combines images while preserving transparency effects.

• Setting A Canvas (Index)

Select the Canvas tab.
A canvas is a background for the image and its mask, which can be positioned anywhere over it.
The size of the canvas is determined by the aspect ratio of the paper type. It is the smallest rectangle with the given aspect ratio that can contain the image.
The custom paper type is selected here.
In this case a custom canvas image is set by pasting an image copied form the photos library.
Note that the custom canvas image is scaled to fit the image, rather than scaling the image to fit the canvas.
Use the 'Image Scale and Position' slider to scale down the image.
Use the 'Image Scale and Position' sliders to position the image in the corner of the canvas.
Add opacity to the border.
Maginify the preview and drag the image to an app that can accept the drag, such as the Finder desktop on the Mac. Or use the export button to share the image in the usual ways (Messages, etc.)
Result.
Recurse by using the result as the new image.

What is a mask?

An image with transparent areas can act as a mask for another image by determining which parts of the second image are visible, partially visible, or hidden based on the transparency levels of the masking image. Here's how it works:

  1. Alpha Channel - Transparency in an image is controlled by its alpha channel, which represents the opacity of each pixel. The alpha values typically range from 0 (completely transparent) to 1 (completely opaque).
  2. Masking Concept - When an image is used as a mask over another underlying image, the alpha channel of the mask dictates the visibility of the corresponding pixels in the underlying image. Opaque areas (alpha = 1): Fully reveal the underlying image. Transparent areas (alpha = 0): Fully hide the underlying image. Semi-transparent areas (0 < alpha < 1): Partially reveal the underlying image, blending it with the background or other layers.

Example: In this example the mask is the word LOVE, where the black pixels are opaque and all others are transparent. But RoundedPic can invert a mask, where opaque pixels are made transparent and transparent pixels are made opaque. The LOVE mask is inverted and applied to the RAYS image:

Inverted Masks