Blur the Background of a Digital Image

Maybe you have taken a picture of a group of people, and now you want to highlight one individual? Or perhaps you thought you've taken the perfect picture, except something in the background is distracting from the photo?To blur the background of an image with Adobe Photoshop, Paint Shop Pro, or GIMP, try one of the following methods.

Steps

  1. Use a graphic editing application such as Photoshop, Paint Shop Pro, or GIMP.
  2. Open the image file. Choose an image with a good resolution to blur the background.
  3. Use Save As to begin working on a copy of the photo. Never modify your original image.
  4. Determine which areas you want to stay in focus (the foreground), and what areas you want to have blurred (the background).
    • Set the zoom to see the entire image on your monitor; this will help you get an idea of where to make your selections.

Photoshop: Quick Method

  1. Select Layers > Duplicate Layer. This will stack a second, identical layer over your original image.
  2. Select Filter > Blur > Gaussian Blur. This will blur the entire image; you’ll work backwards from here.
    • Play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
    • Make sure you’re working on the top layer when you add the blur.
  3. Erase your subject(s) back into focus. Since the original layer is still intact beneath the blurred one, using the eraser tool on your top layer will expose the clear image underneath.
    • Select the Eraser tool from the toolbar to the left.
    • Adjust the eraser size as you go. For larger swaths, use a large eraser; for details and edges, use a smaller, more precise eraser.
    • Adjust the eraser opacity as you go. For large, interior areas, use a high opacity to erase as thoroughly as possible; for edges, lower the opacity to create a softer, subtler effect. Running a low-opacity eraser over the same place multiple times will have a cumulative effect, so err on the side of low opacity where necessary.
  4. When you’re completely satisfied, go to Layer > Flatten Image. This will combine your various layers into one.

Photoshop: Detailed Method 1

  1. Select the Lasso Tool from your tool palette. You’ll use this to select the image(s) in the photo that you want to distinguish from your blurred background. Choose the selection type based on what is most suitable for your particular image. Ex.:
    • If the image you want to emphasize has very straight edges, right-click to change the lasso to Polygonal, which will create straight lines between the points you click.
    • If there’s a sharp, clear edge between the background and the image you want to emphasize, change the lasso to Magnetic, which will find the edge for you.
  2. Increase the feather to between 1 and 3 pixels. Feathering your edges will make them softer and subtler – and much more forgiving.
  3. Zoom in on your subject(s) so that you can see the edges clearly. This will help you freehand-select more accurately.
  4. Click or drag the Lasso tool along the edges of your subject. Be sure to “close the circle” by ending up back where you started and clicking on your origin point. You’ll know your selection is complete once a dotted “marquee” line appears around the edges.
    • Make sure you’re working on the top layer when you lasso.
    • To add to an already-completed selection, hold down the Shift key while you continue to select. This is a great way to either modify your current selection or simultaneously select a separate subject.
    • To subtract from an already-completed selection, hold town the Alt key and select the area you wish to remove, which will then become unselected.
  5. Copy the foreground selection by pressing Ctrl-C.
  6. Paste the foreground selection over top of the existing image. This will create a new layer on top of your original one.
    • Usually, this will paste the copied image directly on top of the original one, which means it might not look like anything has changed. Look at your Layers tab (usually in the bottom right-hand corner) to see if a new layer has appeared.
    • If this "Layers" toolbar is not visible in Photoshop, go to Window and select in Layers the drop-down list.
    • If necessary, use the Move tool, which looks like a cursor arrow, to drag the newly-pasted foreground on top of the existing image so that they match.
  7. Select the layer that contains the original image. This is found in the Layers toolbar.
  8. Go to Filter > Blur > Blur More. This will blur the background but not the duplicated image of the subject.
    • Repeat this Blur More command until you achieve the desired effect. In Photoshop, the Ctrl F keyboard shortcut will repeat the last filter command.
    • Alternately, use Gaussian Blur and play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
  9. Make sure your foreground doesn’t appear too sharp. The easiest way to do this is to look at the History toolbar and undo some of your Blur More commands. Alternately, changing how your layers combine can produce nice effects. To do this:
    • Try changing the newly copied foreground layer's Opacity. This is visible in the Layers toolbar. A good opacity level to start at is 50%; move up a little at a time until you find a good blend.
    • Try changing how the layer combines with other layers by changing its property, also available in the Layers toolbar. For example, try Darken instead of Normal for an artistic sketch effect.
  10. Use the Blur Tool to soften the edges of your in-focus foreground. This should be on the same toolbar as the Lasso Tool.
    • Set the blur tool's strength to somewhere around 33%.
    • Set your brush size to a comfortable level such as a radius of 5 to 15 pixels. If you don't see a brush size option, select Brushes from the Window menu in Photoshop.
    • Use the blur tool to touch up the outside edge of your foreground, especially where the image seems pixelated. This will help to create a sense of transition between your foreground and background that is easy on the eyes.
  11. When you’re completely satisfied, go to Layer > Flatten Image. This will combine your various layers into one.

Photoshop: Detailed Method 2

  1. Select Layers > Duplicate Layer. This will stack a second, identical layer over your original image.
  2. Select the Lasso Tool from your tool palette. You’ll use this to select the image(s) in the photo that you want to distinguish from your blurred background. Choose the selection type based on what is most suitable for your particular image. Ex.:
    • If the image you want to emphasize has very straight edges, right-click to change the lasso to Polygonal, which will create straight lines between the points you click.
    • If there’s a sharp, clear edge between the background and the image you want to emphasize, change the lasso to Magnetic, which will find the edge for you.
  3. Increase the feather to between 1 and 3 pixels. Feathering your edges will make them softer and subtler – and much more forgiving.
  4. Zoom in on your subject(s) so that you can see the edges clearly. This will help you freehand-select more accurately.
  5. Click or drag the Lasso tool along the edges of your subject. Be sure to “close the circle” by ending up back where you started and clicking on your origin point. You’ll know your selection is complete once a dotted “marquee” line appears around the edges.
    • Make sure you’re working on the top layer when you lasso.
    • To add to an already-completed selection, hold down the Shift key while you continue to select. This is a great way to either modify your current selection or simultaneously select a separate subject.
    • To subtract from an already-completed selection, hold town the Alt key and select the area you wish to remove, which will then become unselected.
    • Don’t worry about making your selection perfect the first time around; you will adjust it later.
  6. Go to Select > Inverse. This will select your background instead of your subject(s).
  7. Go to Filter > Blur > Gaussian Blur. This will blur the background of your image.
    • Play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
  8. Go to Select > Inverse. This will re-select your subject(s) instead of your background.
  9. Go to Layer > Add Layer Mask > Hide Selection. The subject of your photo will disappear from the top layer, revealing the intact image from the layer underneath.
  10. Use the Brush tool to modify your selection. It may seem like a mistake to “paint” over your photo, but what you are really modifying is the size and shape of the “hole” between your top and bottom layer. In other words, this is a way of fine-tuning that lasso selection you made originally.
    • Use black to hide more of your top layer. For example, if the blurring overlaps your subject in places, use a black paintbrush to hide some of that top-layer blurring.
    • Use white to show more of your top layer. For example, if the blurring isn’t close enough to the edges of your subject, simply fill in the gaps with a white paintbrush.
    • Be sure to use shades of gray. Especially for edging, it’s important to keep the look soft and subtle, which will make errors harder to detect.
  11. When you’re completely satisfied, go to Layer > Flatten Image. This will combine your various layers into one.

Paint Shop Pro: Quick Method

  1. Select Layers > Duplicate. This will stack a second, identical layer over your original image.
  2. Select Adjust > Blur > Gaussian Blur. This will blur the entire image; you’ll work backwards from here.
    • Play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
    • Make sure you’re working on the top layer when you add the blur.
  3. Erase your subject(s) back into focus. Since the original layer is still intact beneath the blurred one, using the eraser tool on your top layer will expose the clear image underneath.
    • Select the Eraser tool from the toolbar to the left.
    • Adjust the eraser size as you go. For larger swaths, use a large eraser; for details and edges, use a smaller, more precise eraser.
    • Adjust the eraser opacity as you go. For large, interior areas, use a high opacity to erase as thoroughly as possible; for edges, lower the opacity to create a softer, subtler effect. Running a low-opacity eraser over the same place multiple times will have a cumulative effect, so err on the side of low opacity where necessary.
  4. When you’re completely satisfied, go to Layers > Merge > Merge All. This will combine your various layers into one.

Paint Shop Pro: Detailed Method

  1. Select Layers > Duplicate. This will stack a second, identical layer over your original image.
  2. Select the Freehand Selection tool (which looks like a lasso) from your tool palette. You’ll use this to select the image(s) in the photo that you want to distinguish from your blurred background. Choose the selection type based on what is most suitable for your particular image. Ex.:
    • If the image you want to emphasize has very straight edges, change the selection type to Point-to-Point, which will create straight lines between the points you click.
    • If there’s a sharp, clear edge between the background and the image you want to emphasize, change the selection type to Smart Edge, which will find the edge for you.
  3. Increase the feather to between 1 and 3 pixels. Feathering your edges will make them softer and subtler – and much more forgiving.
  4. Zoom in on your subject(s) so that you can see the edges clearly. This will help you freehand-select more accurately.
  5. Click or drag the Freehand-Select tool along the edges of your subject. Be sure to “close the circle” by ending up back where you started and clicking on your origin point. You’ll know your selection is complete once a dotted “marquee” line appears around the edges.
    • Make sure you’re working on the top layer when you freehand-select.
    • To add to an already-completed selection, hold down the Shift key while you continue to select. This is a great way to either modify your current selection or simultaneously select a separate subject.
    • To subtract from an already-completed selection, hold town the Control key and select the area you wish to remove, which will then become unselected.
    • Don’t worry about making your selection perfect the first time around; you will adjust it later.
  6. Go to Select > Inverse. This will select your background instead of your subject(s).
  7. Go to Image > Blur > Gaussian Blur. This will blur the background of your image.
    • Play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
  8. Go to Select > Inverse. This will re-select your subject(s) instead of your background).
  9. Select Masks > New > Hide Selection. The subject of your photo will disappear from the top layer, revealing the intact image from the layer underneath.
  10. Use the Paintbrush tool to modify your selection. It may seem like a mistake to “paint” over your photo, but what you are really modifying is the size and shape of the “hole” between your top and bottom layer. In other words, this is a way of fine-tuning that lasso selection you made originally.
    • Use black to hide more of your top layer. For example, if the blurring overlaps your subject in places, use a black paintbrush to hide some of that top-layer blurring.
    • Use white to show more of your top layer. For example, if the blurring isn’t close enough to the edges of your subject, simply fill in the gaps with a white paintbrush.
    • Be sure to use shades of gray. Especially for edging, it’s important to keep the look soft and subtle, which will make errors harder to detect.
  11. When you’re completely satisfied, go to Layers > Merge > Merge All. This will combine your various layers into one.

GIMP: Quick Method

  1. Select the Free Select tool (which looks like a lasso) from your tool palette. You’ll use this to select the image(s) in the photo that you want to distinguish from your blurred background.
  2. Zoom in on your subject(s) so that you can see the edges clearly. This will help you free-select more accurately.
  3. Click or drag the Freehand-Select tool along the edges of your subject. Be sure to “close the circle” by ending up back where you started and clicking on your origin point. You’ll know your selection is complete once a dotted “marquee” line appears around the edges.
  4. Go to Select > Feather to soften your selection. A good place to start is between 1 and 3 pixels. The higher the number, the softer your edges will become.
  5. Go to Select > Invert. This will select your background instead of your subject.
  6. Go to Filters > Blur > Gaussian Blur. This will blur the background of your image.
    • Play around with different blur radii to create the background effect you want. The larger the radius, the blurrier the image, so if you’re going for a subtle effect, aim low. For example, if you want the background to be very soft and only somewhat identifiable, try a radius of 10. If you want your background just barely blurred, use a radius of .5 or 1.
  7. Go to Select > None to release your selection.

Tips

  • The higher the megapixels of your camera, the better your image resolution will be. It is difficult to enhance a picture with a lower resolution.
  • Be very precise in outlining your foreground; otherwise, it will look choppy.
  • Using digital editing to blur the background does not create true depth because it blurs everything in the background uniformly rather than independently based on distance from the lens. If you are using Photoshop CS2 it now offers a 'smart blur' option in the filters sections under blur. The filter takes into account the depth of field and perspective and applies more blurring to pixels it interprets as farther away and less to pixels perceived as closer to the subject. The filter is also adjustable so it is better to gradually add the effect until you have the look desired.
  • This technique produces somewhat artificial looking images. If you want a more natural look, blend your blur so it truly only affects items in the background. In the example above, if the grass in front of the child were still sharp it would more accurately simulate a narrow "depth of field", which would look more natural.
  • Before making any alterations to a photograph, make a copy, then convert the copy to 16 million colors, if it is not already set for 16 million colors. All of the algorithms in these digital darkroom programs work better in 16 million colors than in other modes.
  • Some digital editing programs have a feature known as zoom blur that allows you to pick a point in your image and blur out from that point.

Warnings

  • Make sure you save frequently! If your computer freezes during this process you will lose all of your progress.
  • Make sure you do not save over your original file! Once your image file is overwritten, it is gone for good if that was your only copy.

Things You'll Need

  • Adobe Photoshop, Paint Shop Pro, or GIMP
  • A digital image of adequate resolution
  • A drawing tablet is a recommended tool to make precise selections.

Related Articles

Sources and Citations

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