recolouring a bitmap

DW
Posted By
Dave_Woodward
Feb 17, 2004
Views
370
Replies
8
Status
Closed
Folks,

am looking for some technique guidance really.

I have a bitmap that represents a flatened car body. you can see it at www.bammaconsulting.co.uk/testsite/bra1.bmp (750kb). The flattened image gets used in an application later on in a process that i won’t go into. Anyway. The car is currently green and I want to turn it red.

My attempts to do this by selecting the green area and thhen using hue and saturation to change the colour certainly do just that, but at the expense of the ‘reality’ of the paintwork. it looks flat and dull without any of the original shine.

Can anyone give me a pointer as to how i can change the colour of the paintwork without losing that great shine effect?

Oh, and if possible, speak slowly as I am a relative PS newbie. PS7 by the way.

Cheers

Dave
Related Tags
bitmap

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TF
Timothy_Fuicci
Feb 17, 2004
Is that a UV texture?
RW
Rene_Walling
Feb 17, 2004
Have you tried a Channel Mixer adjustment layer.

You can mask off the areas that should stay the same and you should be able to keep the realism OK

Is that a UV texture?

Sure looks like one
P
Phosphor
Feb 17, 2004
Man, that was weird.

First time I ever saw an image open in my browser that window shaded from the bottom up instead of building from the top downward.
DW
Dave_Woodward
Feb 17, 2004
OK, this looks really useful.

I can see that the channel mixer is better than the hue control to maintain the realism, but its also much more complicated. I could do with some pointers on how to move the mixer controls to get a red instead of a green. Or am I always going to be fighting against the original green?

I have no idea what a UV texture is, so I can’t comment. I obtained the bmp from somewhere else, so I have no idea how it was created, just that I need to change it.

Thanks folks.
TY
Temekono_Yaro
Feb 17, 2004
have no idea what a UV texture is

It’s where the polygons in a model are mapped out and flattened in such a way as a texture can be applied accurately.
RW
Rene_Walling
Feb 17, 2004
It’s where the polygons in a model are mapped out and flattened in such a way as a texture can be applied accurately.

A 3D model of course, think 3DSMax, Maya etc…

I can see that the channel mixer is better than the hue control to maintain the realism, but its also much more complicated. I could do with some pointers on how to move the mixer controls to get a red instead of a green.

Try these settings as a starting point:

output Channel Red: 100% Red, 100% green, 0% blue

output Channel Green: 0% Red, 0% green, 0% blue

output Channel Blue: 0% Red, 0% green, 50% blue

Play with it until you get the colour you want, and don’t forget to mask unchanged areas

Or am I always going to be fighting against the original green?

No, that’s the beauty of the Channel Mixer.
JS
John_Slate
Feb 17, 2004
you can also try hue/saturation with "colorize" checked.
DW
Dave_Woodward
Feb 17, 2004
Wonderful.

Is there any article that you can point me at to try to understand how the settings you suggested make a nice bright red?

I realise that I can just push the sliders around for a while to see what the result is, but it would be nice to try to understand the theory as well.

Anyway. Many thanks for such a fast and useful response.

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