Mixing two neighbor colors

[LucasBS]

I have two stripes of different colors going side by side (like a solid rainbow)

I'm looking for a brush-like tool that can soften the transition between these colors

Example: a black and a white strip. This supposed tool would create a soft transition of shades of grey between the strips while I pass this "brush" on.

Does it exist on photoshop ?

[JJMack]

Use the blur tool or smudge tool as a brush to soften the line beteen the stripes or or select the hard devid area and use a blur filter. 

[LucasBS]

Hello

Testing here

The Smudge tool "drags" one color on top of the other, but doesn't mix them.

The Blur tool quite does the job, but it destroys detail/tetxure

My opening post was a simplification: I'm retouching photos and manipulating textures on a very small scale, not only solid colors or solid shapes (and that's a challenge that the Blur > Gaussian Blur takes a beat, as it would require complex selections in this case).

My favorite tool, so far, has been the Clone Stamp Tool, which copies the texture, and, controlling the hardness, creates this "blend". But it doesn't work always. Sometimes there's too much difference between the colors, and it acts like the Smudge above

Thank you for the assistance, so far.

[gangeek]

dude. mixer brush is your friend

and yes, smudge tool DOES mix colors between the two. look at the 'scattering' options in the brush panel.

[Chuck Uebele]

Maybe try frequency separation. Do the separations, the you can blur the color/tonal values on the one layer, while retaining the detail on the other. You can make a selection of the areas, then blur, use the mixer brush, or whatever method you want to blur.

[Conrad C]

You might try the Mixer Brush tool set to one of the colors. The Mixer Brush tool is a blending tool.

Paint with the Mixer Brush