Transparent image turns into black squares in PDF form

Try Preferences > Page Display > 

Under Page Content & Information,

Uncheck Show Transparency Grid

Go to the source document and print to Adobe which will save it as a PDF file. This instruction is actually in the Acrobat program if you go to "help" and type in convert png to pdf. I just did that after trying all other options.

I did rename the file extension from .png to .jpg and entered the file as jpg. When it was pasted, it was working just like a png file and didn't have the dark background.

I JUST dealt with this (have before but forgot how...had to re-figure out). I had set my graphics images in file to "Grayscale" because I knew I was printing black and white and grayscale is the best reproduction for black and white especially of photos. When I went back to my original Word file (I use Ultra Office), I changed the graphic type settings to "Default" and that fixed the problem for several different images. Try this.

I figured out that in order to be able to insert transparent images in PDF using Acrobat Reader, the image file has to be converted into PDF version with transparent background. It doesn't recognize transparent JPEG, PNG, etc which will cause the background to be black. I wish this can be fixed so that it will be easier to upload transparent image files without having to convert into PDF.