Editing Decal files for printing - changing light blue background to white?

Before I get to my question, a sincere "Thanks" to YORF and JimZ for scanning and posting all those plans and decals. I'm an avid BAR because of their work.

Too often, a decal can has the light blue background of the release paper, and what I need is white (so my clear decal paper has clear spaces, not light blue.)

I have not found a nice way to do this, as the "fill" tool in MS Paint sees usually sees many different colors - variations of light blue, so it can't change them all to white.

I haven't figured out how to get Corel to do a "fill" yet, but it will probably have the same problem.

Any ideas?

I'm attaching a decal scan to illustrate.

Apologies if I duplicate another's post...

I use a photo program that has a select all feature. I could try selecting all of that shade of blue then cutting it... Does Corel have that?

Here's a good tutorial with examples:

https://www.rocketryforum.com/showthread.php?26105-Image-Processing-and-Photoshop

Definitely switch to something like Gimp or Paint 2.0. Free and way more powerful than MS Paint.

FC

I use Corel Draw and I import the raster scans and create a vector drawing by tracing over the bitmap image. It's work, but once created, it's easy to up and down scale.

Here's a method i haven't tried yet but i'm going to try it for myself. This method is kind of like making a photographic mask. Just using ms paint save the file 2 copies original and 2 color bitmap. Open the 2 color bitmap save it as a 16 color bitmap . Take this same file and fill the now whitened areas with a non used color from the original file ie green. Fill the black areas with white and save the file. Copy the whole image and paste it onto the original unaltered file. Fill the green with white and viola there you have it. I would imagine that this method only works well with starting colors close to black. If you have more lighter colors you will probably have to save it first as a 16 color bitmap and fill colors with black that you want to save.

Paint.net will let you select by color then, by adjusting the percentage slider, automatically add or subtract based on color similarity. Once you've removed the offending background, insert a new layer of all screaming orange or green and move it behind your image. That will help you ensure that you eliminated the offending background. When done, delete the back layer and save it as a gif, png or tif to preserve the transparency.

Thanks to all, who took the time to reply.

I downloaded paint.net, and was able to modify decals as desired, with lots of practice.

Ross