Adding alpha (transparent) background to jpeg images, logos

- Some posters, powerpoints, have non-white backgrounds. Company logos with transparency look nicer on these. However, sometimes logos are only available in the jpeg format.

- Tools like GIMP/KolourPaint will easily flood-fill the white as alpha, except for the closed figures like "O,e" letters. This can be done by hand, than the result saved as png with alpha channel.

- However, jpeg images are full of shades of white, so the result can be very messy sometimes.

- Solution: use advanced software such as ImageJ, to change the contrast so any intensity value say, above 250/255, will be brought to 255. Then automatic flood-fill of the other software programs will be a lot more efficient.

Note: as of 03/2015, ImageJ does not natively support the alpha channel, so other paint software is still required to finish the job.