Resize Algorithm in PowerPoint

Question

What is the algorithm used in PowerPoint when I resize the image? Looks like linear interpolation to me.

Answer 1

Unless you allow PowerPoint to compress the image, it doesn't actually change the data it stores internally. 

But of course it must, in most cases, resize the image before it can display it on the computer screen.  And when it does this, it also antialiases the image.  It does this even if the image is already the correct size for the screen display. 

Knowing the resizing algorithm might be intereresting but would it be useful, since we can't change it ... it is whatever it is.

---

Steve Rindsberg PowerPoint MVP PowerPoint FAQ: http://www.pptfaq.com PPTools Add-ins: http://www.pptools.com

Answer 2

Sign, it's really un-scientific to process the images in PowerPoint. There is nowhere I can tell if my images was change or distorted by PowerPoint. Even I do not the resize algorithm used here. Bilinear? Bicubic?

Answer 3

Aha, thanks.  I don't think it's the resizing algorithm at work here, though it might play some part in things. 

But PowerPoint has always antialiased (read:  blurred) inserted images slightly. 

Mostly it's a good thing, but sometimes it works against you, and unfortunately, there's no way to turn it off.

---

Steve Rindsberg PowerPoint MVP PowerPoint FAQ: http://www.pptfaq.com PPTools Add-ins: http://www.pptools.com

Answer 4

For example, I insert a bitmap picture into PowerPoint and then resize the picture, either enlarge or shrink it. The result looks blur or smooth than original image even if I enlarge first and than shrink it back to original size. So, PowerPoint defiantly did something to the picture. I like to know exactly what PowerPoint did.

Answer 5

Resize what image, exactly?

---

Steve Rindsberg PowerPoint MVP PowerPoint FAQ: http://www.pptfaq.com PPTools Add-ins: http://www.pptools.com