Inserting a graphic image, such as a logo, into a PCB design so that it prints properly, can be a bit tricky. It's a topic we've written about in the past on our blog (Tips for Adding Fonts & Graphics on a PCB). Of course, it's not difficult to insert an image into a design in DipTrace (or PCB Creator), however, it can be difficult to get the image to display the way you expect on the manufactured PCB.
To insert an image into a design, simply navigate to Objects > Place Picture. Draw the location area for the image and select the desired image. And, our recommendation is to insert the image as a part of your silkscreen layer(s).
But, how do you know how the image will actually look when it's manufactured. For DipTrace users, we would recommend you export the final data to Gerber, and use our InstantDFM tool to receive a DFM report. Once your design has uploaded, select the Summary tab to receive an image of the design. Look good? Great! Doesn't look good? Well, then adjustments are needed, because whatever you see here is what you should expect to receive from your manufacturer. (PCB Creator users who are unable to export to Gerber, can email their source .bac file to email@example.com and request a DFM report.)
So, what are some reasons why an image would need to be adjusted? One reason is you might see "white" where you expect to see transparency. Another reason is that you might see the inverse of the image. It's difficult to cover every scenario here, but here are a few tips to get you on the right path.
First, make sure you start with a high quality image. That 12kb 72dpi .png file you grabbed from a Google search just isn't going to look sharp.
Second, using a graphic editor, convert your image to black and white. Colors such as green don't print well over green soldermask, even if the specification calls for white silkscreen to be used. Using the free graphic editor, Gimp, there are a handful of different options to convert an image to black and white.
Third, sharpen the image as desired. Using Gimp, navigate to Tools > Color Tools > Threshold to adjust the threshold value and the conversion of the color picture to black and white.
Finally, it may be necessary to invert the image after the conversion from color to black and white. Black objects on the image will become white silkscreen lines on the PCB. White areas will be ignored (or transparent).
That's it! Save your revised image and place it back into the silkscreen layer of the PCB design. Run another DFM check to verify the image is displaying as desired and send the design off to production.