How to whiten up a white background?

[pipkato]

I have some people against some white walls and would like to be able to mask them and make the white wall whiter and cleaner.  Can't seem to find out how in the tutorials.  Can someone suggest a way for a relative novice?

 

Thanks!

[toltec]

Without seeing the image, a bit hard because there are lots of methods, each one depending on what is there.

It might be possible to get away with using a Shadows and Highlight Adjustment and just adjust the highlights, Failing that, an easy method to try. . .

Select the wall and refine the edges as necessary. Select > Refine Edges

Go Layer > New Adjustment Layer > Levels and simply adjust the White Level slider. The selection will mask the Adjustment to the selected area only. i.e. the Wall

I selected the sky and used that to simulate a wall.

 

 

 

[smadell]

There are SO many ways to do this, it boggles the imagination. Most of them involve separating the walls from the rest of the photo, and for that you need to select the walls. If there is enough contrast between the "white" walls and the rest of the photo, this will make it easier.

I'm going to show you just a couple of suggestions that come to mind. For this, I downloaded a photo from Google Images - I believe it's a stock photo, and is probably protected by copyright. For educational purposes (this forum) this should be considered "Fair Use," but I'm sure the photo is otherwise protected.

Method 1: Use the selection brush to select the man only. Use the "Refine" button to get a cleaner selection, and choose "Apply" to get the man selected. Now, invert the selection (this leaves you with everything BUT the man selected). Copy and Paste. This will copy ONLY the selected area (i.e., the walls). Do what you will to the walls. In this example, I put a Levels adjustment in as a child layer, so that it only affects the walls layer.

Method 2: Use the selection brush to select the man, refine, and invert (just as in the first example). With the walls selected, place a Curves adjustment into the Layers stack. Because you did this with the walls selected (but the man NOT selected) the Curves adjustment will have a built in mask that allows it to act only on the walls.

Method 3: A little bit more complicated. Use the selection brush to select the man, refine, and invert (again in the same manner as Method 1). Now you've got the walls selected. Insert a new pixel layer into the Layers stack. WITH THE SELECTION STILL ACTIVE, choose the paint brush tool and select white. Make the opacity of the brush less than 100% (for this example, I chose 50%) and set the Brush Blend Mode (in the Context Toolbar) to OVERLAY. Now brush over the selection. The brush will whiten up the white areas, but will leave the blacker areas alone.

There are probably a zillion other ways to do what you're looking for. These are just a few that I thought of.

 

[firstdefence]

@smadell Use Pixabay for images that you can use for examples, its a great site.

[firstdefence]

I've just tried Shadows and Highlights set to Screen mode, and it really whitens walls up. I masked the girl off first a bit roughly but it gets the boggliness over. Changed the image to full scale to better see the effect.

Fresh coat of Shadows and Highlights oddly all set to 0% and blend mode set to screen

 

Original image

 

[pipkato]

Thank you all very much for all that great advice - Toltec, FirstDefence, Smadell.

I'll give those methods a try.  It's great to know there are so many alternatives.

Thanks again!

[pipkato]

One final quick question.  I just tried the 'Select/Refine edges' suggestion but 'Refine Edges is greyed out.  My image is in black and white.  Is that the reason, or should I have done something before the 'Select/Refine Edges' command?

Thanks!

[firstdefence]

send a screenshot of the Affinity Photo app window and we can tell you better.

But in the meantime check you have the selection tool selected.

[pipkato]

Thanks firstdefence.  I'm going to do some more experimentation with selection tools in general.  I did manage to get 'Refine Selection' to display, but still don't know how.  My image is an old relatively flat black and white shot.  But I think I can learn a lot from trying the various methods advised above.  If I draw a complete blank I might post it here.  Thanks again.

[AffinityJules]

Another method is to use the 'apply image' technique. I must confess I don't understand how the heck it works or what the letters next to the adjustments mean - it's all gobble-de-gook to me. But I did this in about 30 seconds, and of course. . .with a bit of patience and mucking about a better result can be achieved.