bitmaps & DPI

[Steve Clarkson]

So I have this bitmap image of a sword.....I used Corel Paint to remove the background, but it was still in a "white box".

I engraved it at 600 dpi (100s/40p) on a piece of acrylic and it engraved beautifully.

Then I engraved it at 1200 dpi (5s/100p) using cermark on a piece of metal, and the white box actually engraved!!! I've never had anything other than a black line or fill that has engraved before.

Any idea why a "white box" would engrave? Was it because I upped the dpi?

[Mike Chance in Iowa]

Was it truly white? i.e. 255, 255, 255 RGB colors? I've had problems in the past when I thought it was a true white, but it was really 254, 254, 254 and so forth with just a fraction off from true white.

[Joe Pelonio]

Yes, you answered your own question. The white box was not detailed enough to show up until you increased the dpi.

[Frank Corker]

Mike nailed it too. It's not white, it's a fraction off and the laser engraves everything other than white.

[George M. Perzel]

Another trick........
After you remove the background, make a new layer and save it as a TIF file with a transparent background. When you import it into Corel, there is no background to interfere with other objects if you are trying to build an image.
Best regards;
George
LaserArts

[Dan Hintz]

Yes, you answered your own question. The white box was not detailed enough to show up until you increased the dpi.

Joe,

Isn't that like saying "it's not zero until you multiply it by a big enough number"?

[Steve Clarkson]

That worked perfectly.......thanks George!