Select specific white range in complex image

An alternate approach would be to do the following:

Open the file and remove the top two layers. Duplicate the bottom layer and then change the Mode to Lab Color. Do not flatten.

Choose Channels and within it choose the  b  channel which houses the Blue information. Drag the blue channel down to add an Alpha Channel. It will look similar to the middle swatch shown here.

Select the Alpha channel, Edit > Copy it, then move to Layers and Paste it as an additional layer in the Layers panel.

To stretch the range of this seemingly monotone layer choose Curves and within its drop-down display, click on Auto. The image will look similar to the rightmost swatch.

The darkest tones represent blue, the lightest tones represent what you referred to as degrees of white. The objective now is to remove the darker tones. You will control the degree of blue tones to be eliminated. Here’s how:

Add a transparent layer below the topmost layer and turn off all layers below the transparent one.

Return to the top layer, and enlarge the view similar to one pictured here.

Click on the layer to bring up Layer Style and choose Blend if. Move the top slider as shown and as you do that you will remove dark tones leaving an array of light tones. You will determine at which point sufficient dark areas have been removed leaving the variety of lighter values you want to isolate.  

Not shown:

For a smoother transition Option/click on the slider to split it, then drag the right half slowly to the right. 

Flatten the image  return to RGB and save as a psd file.

Note: The marker indicates a dark tone I chose as a dark-tone guide as I applied the slider

If you're talking about the white, or lighter shades in the sweater, I would use color range.

I do not see any White in you document. Layer 2 is empty. Layer 1 the visible copy of the label on the Sweater in Layer 0.  

Look like the sweater was cutout with the pen tool from a white background.