Blending modes: Mutiply, Screen and Overlay
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[imgr][/imgr]Blending modes: Mutiply, Screen and Overlay
Tutorial by Pathfinder.
This section covers three commonly used Blending Modes - Multiply, Screen, and Overlay. These three Blending Modes are used frequently by photographers for image processing.
Nikolai has already discussed the Normal Blending Mode, as well as Dissolve, Difference and Exclusion. Therefore, the reader is expected to know, and understand, the basics of creating a duplicate layer with the command CTRL-J ( Apple-J on the MAC) to create a copy of the background layer in the Layers Palette. This is done when using the Multiply or Screen Blending Modes.
The reader is also assumed to know how to use the Opacity Slider in the Layers Palette to modify the intensity of the Blend Mode being used.
The Overlay Blending Mode may be performed with a new solid color layer of medium gray, or may simply be brushed onto the image with the Brush Tool.
Here is an image of a white barn that looks a little too bright. We can darken it with the Multiply Blending Mode.
The Help section in PSCS 2 says about Multiply Blending "Multiply looks at the color information in each channel and multiplies the base color by the blend color. The result color is ALWAYS a darker color. Multiplying any color with black produces black. Multiplying any color with white leaves the color unchanged. When you’re painting with a color other than black or white, successive strokes with a painting tool produce progressively darker colors. The effect is similar to drawing on the image with multiple marking pens."
Martin Evening in his "Adobe Photoshop CS2 for Photographers" says "the Multiply Blending Mode Multiplies the base by the blend pixel, except where the blend color is white" So what are these paragraphs really saying?? The darker the pixel in the top layer, which is multiplied by the base pixel beneath it, the darker the resultant final pixel. Black in the upper layer (blend) give the darkest pixel, and white (upper layer ) causes no effect.
So, with Multiply Blending, we CAN darken a moderately over exposed image.
If you open an image and duplicate it on the Layers Palette with a CTRL-J ( or Apple-J on the MAC) and then use the Multipy Blending Mode, the result is a significantly darker image overall, similar to sandwiching two Kodachromes together in a slide projector. The Opacity slider can then be used to diminish the effect from 100% down to a not discernible 1%.
Duplicate the barn image with CTRL-J(Apple -J) and you will have two layers, the background and the upper layer. If these are then Multiply Blended, they will become significantly darker.
Here is the barn image after being duplicated in the Layers Palette and then applying the Multiply Blending Mode at 100% (If the effect is not strong enough, just hit CTRL-J a second time for an additional blending layer and see the effect grow right before your eyes.)
Maybe that is just a little too much, so let's slide the opacity slider back to 50% for this image. Now we're getting somewhere.
Of course, as Nik demonstrated so well, masks can be used to limit the effects of the blending modes, and that is also true with the Multiply blending mode. Blending Modes are not limited to the RGB channels either. You can convert the image to LAB, and then use the Blend IF commands to limit the Multiply Blending Mode to just a limited portion of the Lightness or the A or B channels. This can be used to darken a sky without doing any selections first, just letting the color of the sky act directly through the B channel to limit the effect to the blue pixels only.
Here the image was duplicated with CTRL-J and then switched to LAB. In the Layers Palette, the Blend If command was selected from the drop down menu elicited by the Blending Options button in the upper right of the Layers Palette.
The little arrow on the upper right of the Layers Palette will display a drop down menu when pressed. One of the selections in the drop down menu ellicited, is the Blending Options
The Blending Options dialogue box looks like this.
This Blending Options box is for blending in the Normal Mode, but another selection offered by the Blend Mode box will be Multiply Blending.
This Blending Options box is being used with an image in the LAB color space, as the Lightness channel is selected in the lowest box. This could be changed to the A or B channel also. If the B channel is selected the effect can be limited to the yellow or blue portions of the base image, or some combination of the two by the sliders below the Blend If box.
By moving the image to the LAB color space, and Multiply Blending limited to the blue half of the the B channel, skies that are too thin can be nicely thickened as seen in the last barn image above.
This can be far more precise than trying to do a selection, then feathering it to hide the selection.
Multiply Blending can also be done on the Lightness Channel to darken it and increase its contrast.
The Multiply Blend can also be performed on a single layer of an image with the Brush Tool set to Multiply mode with Black ink, and a light opacity ~ 10-20% with a very soft feathery brush.
Screen Blending is almost exactly the opposite of Multiply Blending. Photoshop CS2 Help command says "Screen Looks at each channel’s color information and multiplies the inverse of the blend and base colors. The resultant color is always a lighter color. Screening with black leaves the color unchanged. Screening with white produces white. The effect is similar to projecting multiple photographic slides on top of each other."
Martin Evening in his book says that "Screen mode multiplies the Inverse of the Blend and the Base pixels, always making a lighter color, except where the blend color is black".
The effect is to lighten an underexposed, too dark image.
Again create a copy of the background layer with CTRL-J(Apple -J or Command-J on the MAC ) and then use Screen Mode to lighten the image. A Mask ( like the luminosity channel inverted ) can be used to help limit the effects only to the darker values.
Here is an image of a wasp that is too dark. ( I picked this image because it could be lighter )
Here is the image after a 100% Screen Blending mode - maybe a little too hot after all.
Tutorial by Pathfinder.
This section covers three commonly used Blending Modes - Multiply, Screen, and Overlay. These three Blending Modes are used frequently by photographers for image processing.
Nikolai has already discussed the Normal Blending Mode, as well as Dissolve, Difference and Exclusion. Therefore, the reader is expected to know, and understand, the basics of creating a duplicate layer with the command CTRL-J ( Apple-J on the MAC) to create a copy of the background layer in the Layers Palette. This is done when using the Multiply or Screen Blending Modes.
The reader is also assumed to know how to use the Opacity Slider in the Layers Palette to modify the intensity of the Blend Mode being used.
The Overlay Blending Mode may be performed with a new solid color layer of medium gray, or may simply be brushed onto the image with the Brush Tool.
Here is an image of a white barn that looks a little too bright. We can darken it with the Multiply Blending Mode.
The Help section in PSCS 2 says about Multiply Blending "Multiply looks at the color information in each channel and multiplies the base color by the blend color. The result color is ALWAYS a darker color. Multiplying any color with black produces black. Multiplying any color with white leaves the color unchanged. When you’re painting with a color other than black or white, successive strokes with a painting tool produce progressively darker colors. The effect is similar to drawing on the image with multiple marking pens."
Martin Evening in his "Adobe Photoshop CS2 for Photographers" says "the Multiply Blending Mode Multiplies the base by the blend pixel, except where the blend color is white" So what are these paragraphs really saying?? The darker the pixel in the top layer, which is multiplied by the base pixel beneath it, the darker the resultant final pixel. Black in the upper layer (blend) give the darkest pixel, and white (upper layer ) causes no effect.
So, with Multiply Blending, we CAN darken a moderately over exposed image.
If you open an image and duplicate it on the Layers Palette with a CTRL-J ( or Apple-J on the MAC) and then use the Multipy Blending Mode, the result is a significantly darker image overall, similar to sandwiching two Kodachromes together in a slide projector. The Opacity slider can then be used to diminish the effect from 100% down to a not discernible 1%.
Duplicate the barn image with CTRL-J(Apple -J) and you will have two layers, the background and the upper layer. If these are then Multiply Blended, they will become significantly darker.
Here is the barn image after being duplicated in the Layers Palette and then applying the Multiply Blending Mode at 100% (If the effect is not strong enough, just hit CTRL-J a second time for an additional blending layer and see the effect grow right before your eyes.)
Maybe that is just a little too much, so let's slide the opacity slider back to 50% for this image. Now we're getting somewhere.
Of course, as Nik demonstrated so well, masks can be used to limit the effects of the blending modes, and that is also true with the Multiply blending mode. Blending Modes are not limited to the RGB channels either. You can convert the image to LAB, and then use the Blend IF commands to limit the Multiply Blending Mode to just a limited portion of the Lightness or the A or B channels. This can be used to darken a sky without doing any selections first, just letting the color of the sky act directly through the B channel to limit the effect to the blue pixels only.
Here the image was duplicated with CTRL-J and then switched to LAB. In the Layers Palette, the Blend If command was selected from the drop down menu elicited by the Blending Options button in the upper right of the Layers Palette.
The little arrow on the upper right of the Layers Palette will display a drop down menu when pressed. One of the selections in the drop down menu ellicited, is the Blending Options
The Blending Options dialogue box looks like this.
This Blending Options box is for blending in the Normal Mode, but another selection offered by the Blend Mode box will be Multiply Blending.
This Blending Options box is being used with an image in the LAB color space, as the Lightness channel is selected in the lowest box. This could be changed to the A or B channel also. If the B channel is selected the effect can be limited to the yellow or blue portions of the base image, or some combination of the two by the sliders below the Blend If box.
By moving the image to the LAB color space, and Multiply Blending limited to the blue half of the the B channel, skies that are too thin can be nicely thickened as seen in the last barn image above.
This can be far more precise than trying to do a selection, then feathering it to hide the selection.
Multiply Blending can also be done on the Lightness Channel to darken it and increase its contrast.
The Multiply Blend can also be performed on a single layer of an image with the Brush Tool set to Multiply mode with Black ink, and a light opacity ~ 10-20% with a very soft feathery brush.
Screen Blending is almost exactly the opposite of Multiply Blending. Photoshop CS2 Help command says "Screen Looks at each channel’s color information and multiplies the inverse of the blend and base colors. The resultant color is always a lighter color. Screening with black leaves the color unchanged. Screening with white produces white. The effect is similar to projecting multiple photographic slides on top of each other."
Martin Evening in his book says that "Screen mode multiplies the Inverse of the Blend and the Base pixels, always making a lighter color, except where the blend color is black".
The effect is to lighten an underexposed, too dark image.
Again create a copy of the background layer with CTRL-J(Apple -J or Command-J on the MAC ) and then use Screen Mode to lighten the image. A Mask ( like the luminosity channel inverted ) can be used to help limit the effects only to the darker values.
Here is an image of a wasp that is too dark. ( I picked this image because it could be lighter )
Here is the image after a 100% Screen Blending mode - maybe a little too hot after all.
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