Easy way to make an image's background transparent


I just ran across an interesting YouTube video on how to use Preview (of all things) to make the unwanted background of an image transparent. This works best if there is a good contrast between the image and the unwanted background.

Copy your image to Preview or open an existing file in Preview. Next select the Show Markup Toolbar icon from the widow tool bar as shown here:


A new second tool bar will now appear below the mail bar and you now select the Instant Alpha icon:


Now you click and drag on the background you want to make transparent and it will change to red. Here is a little video of how the whole simple process works:


At this point you can either save the image or simply select all and copy the image and then directly paste it into your Panorama form in graphics mode. Voila!


This only works, I think, if you don’t have white inside or all items are connected. I have had issues in trying to isolate a logo and the “magic” wand ends up selecting everything, no matter how careful I am.


The Instant Alpha feature is the same as available in Pages. It works on every background color. You can select one pixel of color, and then you drag from this pixel to pixels in the neighborhood. So you select an additional amount of nearby color shades. How good masking a background works depends on a discernible color difference to the foreground.


Well, you certainly don’t have the capabilities you would have in Photoshop but this is a lot quicker for simple projects. I have two versions of Photoshop (CS3 & CS5). In CS3 I can remover the background to transparent, select the object and it will paste directly into a Panorama form as a Static Image and retain the transparency. Using CS5 or later you end up with a white background when you do the same thing. With CS5 you would have to save the image as a PNG file with the transparency option clicked and then use an Image Object in the form to display the file which then showed with the proper transparency. I did find, however, a sneaky way to actually get a copy to the clipboard that maintained the transparent background. I’ll share that info if anyone is interested.


I have to correct my post: The Markup feature in Preview.app is a simple Magic Wand function. You can use it to select the background only or the foreground only. — The Instant Alpha feature in the iWork apps like Pages is much more detailed and is able to mask several color shades (as I described).