The pic itself is not mine as is obvious by the credit in the corner. It is one that I found while scrounging around the internet looking for something even close to what I was thinking of. See, if we're talking about Batmans classic comics costume in live action and if what people are thinking of is that light blue you might have seen in a Jim Aparo comic for example, then yeah that would probably be bad for live action. But my thought is more how BTAS handled it with its dark blue highlight. Also I think the 89 costume is the most faithful at least in terms of the shape of the mask and having the chest area looking like muscle and not armor plating.
What I did was make some adjustments with hue and contrast. For the blue to work it has to be not only dark itself but also lit the right way. The grey still comes out very light unfortunately. I think a darker grey would be preferable.
Now IMO the "trunks" area of this pic is cut too high and I wouldn't want them to use that weird three pronged version of the bat-symbol's tail, and it is an action figure but I think this works to convey the idea of how I think Batman's classic costume could be on-screen. The pic as it originally looked before my adjustments is below.