Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Dinarius on July 28, 2022, 12:18:23 pm

Title: Revealing a new white background without removing some foreground elements?
Post by: Dinarius on July 28, 2022, 12:18:23 pm

This isn't my problem, but it's an easy way to describe it.

I have a photo of a brush shot against off white.

I have created a new pure white canvas, and I want to brush away the off-white ground to reveal the pure white ground.

Is there a way to isolate the red bristles of the brush, so that I can brush over them to reveal the new white round between them, rather than painstakingly zooming in to brush between each bristle?

I hope that makes sense!

Thanks.

D.

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: Wolfman on July 28, 2022, 02:06:45 pm

Would help to see your image but you could make a channel mask of the red bristled brush and then you have the brush isolated against an off white background. Look at your channels of red, green and blue and see which has the most contrast against the off white background. Hope that makes sense.

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: mcbroomf on July 28, 2022, 02:43:25 pm

Select
 > Subject

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: nirpat89 on July 28, 2022, 06:52:06 pm

Quote from: Dinarius on July 28, 2022, 12:18:23 pm

This isn't my problem, but it's an easy way to describe it.

I have a photo of a brush shot against off white.

I have created a new pure white canvas, and I want to brush away the off-white ground to reveal the pure white ground.

Is there a way to isolate the red bristles of the brush, so that I can brush over them to reveal the new white round between them, rather than painstakingly zooming in to brush between each bristle?

I hope that makes sense!

Thanks.

D.

Isn't it better to make a rough mask first and then go refine it in Select and Mask using various tools there.  Once you have a good mask, inverse it and paint bucket the white background. 

:Niranjan.

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: Jeffrey Saldinger on July 28, 2022, 07:34:02 pm

I keep thinking the Color Range tool will be useful to select the “red” and the “off-white.”

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: PeterAit on July 29, 2022, 12:16:41 pm

I assume Photoshop. What about using the Magic wand to select all the background and then delete it, replacing with white?

Title: Re: Revealing a new white background without removing some foreground elements?
Post by: Dinarius on July 29, 2022, 01:00:52 pm

Sorted.

The object was shot against a seamless white background. All of the subject was darker than the white background.


1. In PS create new (255) white canvas, considerably larger than the image.
2. Place the image on top of the canvas.
3. Create layer mask.
4. Choose Select > Colour Range > Highlights
5. Invert.

This gave me the subject against a pure white background, with perfect white between the bristles, without having to do any brushing there.

I only had to use the brush tool to remove shadows I didn’t want. I then flattered the image and cleaned any flaws in the remaining shadow areas.

I ended up with the subject against pure white - which really sets it off - instead of against the off white of the seamless paper. More importantly, the flaws in the seamless (inevitable when moving a large object on it) were eliminated.

D.

Ps. Is it possible to set the brush tool to remove (on a layer mask) anything above a certain luminosity? If so, how? Since all parts of my subject were darker than the seamless paper, this would also work, if it’s possible to do.