How to Make Transparent Images with Preview in OS X

Sometimes, images with transparencies can be quite useful, as you might need to place the same image over different coloured backgrounds, and you want it to properly blend in. A white background will let you easily view the image on your screen, but when you place the image onto a different coloured background, the white colour will stand out as an obtrusive rectangle as shown below:

Transparencies-Preview-White-Rectangle

To help reduce this, you can either manually remove backgrounds from images using Apple’s Preview application or use a transparent canvas to compose images that already contain transparency. Both can be done in Apple’s Preview, and we’ll be showing you how to do both, so keep on reading below!

There are a number of options to create a transparency background in an image that has none. To do this, you simply need to remove a section of the image. We’ve outlined the basic methods below. They are quite easy, which is why we won’t go into many details about each:

1. Using the Basic Rectangle and Elliptical selection tools, you can select the area(s) you want to remove. This can be done by dragging your mouse pointer over the area you want to delete, and by clicking on “Delete” on your keyboard.

Transparencies-Preview-Rectangular-Selection

Transparencies-Preview-Selection-Rectangular

Transparencies-Preview-After-Deletion

2. Use the Lasso Selection Option for a selection that has an irregular shape, and press “Delete” to remove the selected area of the image and make it transparent.

Transparencies-Preview-Lasso-Selection

Transparencies-Preview-Lasso-Selection-Shape

Transparencies-Preview-After-Lasso-Deletion

3. You can use the ‘Instant Alpha’ tool. Drag your mouse pointer to select the image exposure you want to delete. This is a hit-or-miss method which may not work sometimes, but in some cases it will give you quite a smoother way to delete unwanted contents of your image to make it transparent.

Transparencies-Preview-Instant-Alpha-Icon

Transparencies-Preview-Instant-Alpha

Note: These tools might not be shown by default. To enable them, simply click on the “Show Edit Toolbar” icon in the Menu bar as shown below:

Transparencies-Preview-Edit-Toolbar-Icon

These options might not be the best out there, but for free they are relatively good, especially if you would like to clear an area that is defined by a distinct border.

Another method is to create a transparent canvas in Preview, one that will allow you to compile multiple images to create one final image. There are many ways to do this, but the most easy one (albeit a little long) is outlined below:

1. Open an image in Preview according to your clipboard size requirements. This can be any size, but if you want a specific one, search Google for any image of that particular size.

2. Once the image is open in Preview, keystroke ‘Shift+Command+Control+4′. This will enable a cross-hair cursor on your keyboard. Click and drag it over the whole image.

3. Key in “Command + N” which will result in a new file opening with the selection you made earlier. You can also navigate to “File -> New From Clipboard”:

Transparencies-Preview-New-From-Clipboard

4. Click on “Command + A”, followed by the “Delete” key. This will result in a transparent image like below:

Transparencies-Preview-New-file

Transparencies-Preview-Canvas-After-Deletion

Note: Your screen may become grey like the image above, or it may become a checkerboard pattern. Either way, it means the area is transparent.

You’ll now have a blank canvas on which you can place (copy and paste) other images that include transparency. You can set them according to your needs.

Transparencies-Preview-Copy-Image

Do keep in mind, that once any image is deselected, it will become static, and will not be able to be resized/moved again. This may become a difficulty, but you can easily use the “Command + Z” function to undo any error, and start again.

Once you’ve finished, be sure to save your image as a PNG or any other format that supports transparency (JPEG doesn’t!). Now you can use your image in numerous applications that support transparency.

Transparencies-Preview-Save-As-PNG

While there are many, many other premium applications out there that offer these and far more other options for transparent images, Preview is free with every OS X machine, and if you find yourself in need of a transparent hole in an image, or you need to compile a few images that already contain transparency, then you will find the above mentioned methods useful.

If you have any comments/questions/tips, be sure to let us know in the comments below!