How to see / highlight very light colours / whites in PhotoShop?

[SmokeyOrange]

Hi. I am just trying to make white backgrounds with PhotoShop for product shots, and I am doing manual Eraser, but I can't remember how to add a layer to show where the very white colours are i.e. past a certain threshold..

I have done it before where the white colours show up as blacks with a certain effects layer - and so I can see what parts of the photo are not perfect white, and then remove this layer after finishing erasing.

(I need to use Eraser because there are too many whites in the product)

Thanks

[c.pfaffenbichler]

Your workflow seems confusing to me.

Could you please post a screenshot including the Layers Panel?

What exactly do you mean by »white colours« – actually pure 255/255/255 (or 0/0/0/0 in CMYK) or what Tolerance is to be taken into consideration?

Adjustment Layers or Blend is-settings could be employed in highlighting image areas of certain colors.

[SmokeyOrange]

Hi. Sorry. Yes it wasn't very well explained.

Imagine you have now in front of you an image of light grey and several large bright red dots on it.

We can see the bright red dots easily but the light grey it is hard to see.. if I erase a bit of it to make some of the light grey pure white, then we can see the difference between the light grey and the white but it is difficult.. especially if the light grey is very nearly white.

I want to make these 'nearly white' colours highlighted so that I can erase them.

Thanks

[c.pfaffenbichler]

Erasing on a photographic image seems problematic to me because it may clash with the image’s original noise/grain.

Clone Stamp, Healing Brush, … may fit in better, painting on a Layer with a noisy Linear Light Pattern Overlay would be another option.

In any case one should work on a separate Layer or a duplicated Layer in my opinion.

[SmokeyOrange]

Hi. I was looking for the Threshold as mentioned below. Thanks for your time. Chris

[c.pfaffenbichler]

You could still try the Blend if-settings for a Solid Coior Layer (also remember to remove or hide it before finalising the image) as in the screenshot I posted before.

[Norman Sanders]

I am a strong supporter of c.pfaffenbichler​ 's recommendation for the project you described...better than the Threshold method you inquired about. The following are the Blend If steps, assuming the object has crisp edges and no pure whites within or at the edge of the object:

If there is a lock on the background layer holding the image, drag the lock to the trash.

Place a transparent layer below the image layer

Double click on the image layer to bring up Layer Style

In the Blend If section, gently move the right slider to the left until the white disappears.

Flatten the image and save as a psd file.

If the edges are not crisp, after coming close to the object, hold down the Option key and choose the left side of the upper right slicer to split it. Then slowly move the left side of the split slider to ease into the edge of the object.

[SmokeyOrange]

Okay great. That actually looks really good if it does what I think it does. Chris

[SmokeyOrange]

Now I can see the grey bits still on the background from this art product I was cleaning up

[Norman Sanders · Accepted solution]

I believe you are referring to the Threshold method:

From the symbols at the bottom of the Layers panel, select Adjustment Layer (half-black-half-white circle) and from its drop-down menu choose Threshold. You will be presented with a histogram, and below it, a slider. Move the slider all the way to the right; the image will go completely black. Inch the slider to the left until the first white non-specular patch appears. It is the location of the highlight extreme. Choose the Color Sampler tool. (It is nested with the Eyedropper tool in the Tools panel.) Click in that highlight location. The Color Sampler will mark the site. Adjust the slider for near-whites and mark them if you choose. Then trash the Adjustment layer.

[SmokeyOrange]

Yes spot on. I was being stupid. I knew all the right words haha. Thanks

[Lumigraphics]

Forget the Threshold adjustment.

Create a new Levels adjustment layer. Drag the black slider all the way to the right. Duplicate this layer if necessary.

You can adjust it and it works MUCH better than Threshold.