How to replace a colour by another colour using paint.net

Question

I am working on a web template and I want to replace the default red colour by green colour. For example I have this picture:-

Where I want to replace the red with green color.so I did the following steps:-

1. I opened the image using Paint.net, I set the primary colour to be green.
2. Then using the “Paint Bucket” I click on the red area, the result is that the red has been changed to green, but this affected the black text which became less sharper as follow:-

So my question if there is a way inside paint.net to specify to replace all the red pixels to be green instead of using the “Paint Bucket”, so the black text do not get affected ?

Solution

Find the "Tolerance" bar top of the screen and drag it down to 0%. When set to 0%, your paint bucket will only fill in pixels that contain that exact red color. This likely will not change the red in the edges, though. Keep filling in individual pixels or play around with the tolerance meter until you get your desired result. If you do play around with the tolerance meter to fix the edges, you should try drawing a temporary black square (or some color that isn't green/red that you can recolor to green/red later) around the black radio-wave icon so it isn't affected when you fill the edges in at a tolerance other than 0. Be sure to keep your "Flood mode" at contiguous (the light bulb icon).

Note: the "Flood mode" icon (which is probably already set to "contiguous", the light bulb icon) can control whether or not to fill in all of the exact red in the image or just the exact red that touches the area you're filling in. You will probably only need the contiguous option for this task.