| Your photo | What happens to the blur | Planning use |
|---|---|---|
| Portrait mode photo on a supported iPhone (12, 11, XS and XR lines) | A Depth slider changes blur strength after the shot | Try this first. No masking is needed. |
| Older iPhone, or a photo not taken in Portrait mode | The Depth slider is not available | Use an editing app: mark the subject and background, then blur only the background. |
| Any photo, edited in a browser | Pixelcut detects foreground and background, applies a Gaussian blur and lets you set strength with a slider. It accepts JPG, PNG and HEIC up to 50MB and 6000 × 6000px. | Check file type, size and dimensions before uploading. |
| A scene you can still reshoot | A closer subject gives a shallower depth of field | Reshooting can beat editing when the original has no depth information. |
Figures come from the iPhone Photography School blur tutorial and Pixelcut’s background blur tool page.
To see how to blur background of photo already taken, use the Depth slider if it was shot in Portrait mode on a supported iPhone. Otherwise, select the subject in an editor and blur only the background.
If masks and layers are unfamiliar, the basics in our photo editing for beginners guide give useful context. This page covers the specific job of softening a background after the fact.
Choosing a method by device and photo
The right method depends on how the photo was captured and how much control you want over the edges. Four situations cover most cases:
- Portrait mode photo on a supported iPhone: use the Depth slider. It is the fastest route and needs no selection work.
- Older iPhone or an ordinary photo: use an editing app that lets you mark the subject and background, then blur the background alone.
- Desktop with a large file: an editor with selection and masking tools gives the finest control over edges, hair and other awkward outlines.
- Quick fix with nothing to install: a web editor that detects the subject automatically, accepting that you control less.
If your starting point is a print rather than a digital file, digitize it first with How To Scan Photos: A Practical Guide To Digitizing Memories In 2026. Every method below begins from a digital image.
iPhone: the Depth slider and its limits
Portrait mode uses depth-effect software to blur the background as you shoot, according to iPhone Photography School. That is why the blur can be changed afterward: a Depth slider beneath the photo adjusts the blur strength. The tutorial lists the iPhone 12, 12 Mini, 12 Pro, 12 Pro Max, 11, 11 Pro, 11 Pro Max, XS, XS Max and XR as having it, and says it is not available on older iPhones.
For a Portrait mode photo on one of those models, the sequence is short:
- Open the Portrait photo in the editing view.
- Drag the Depth slider beneath the photo to adjust the blur strength.
- Stop when the background is soft but the subject’s outline still looks natural, then save the edit.
If your phone is older, or the picture was taken in a standard mode, plan on the masking approach in the next section instead of looking for a slider that is not there.
Masking the subject in an editing app
When there is no depth effect to adjust, the edit becomes a selection job. The tutorial’s first step in an editing app is to use Smart Selection tools to select the subject and the background, with brush strokes marking each. The quality of that selection decides how believable the final blur looks.
- Brush over the subject, then over the background, so the app can separate the two.
- Check that the app has selected the subject accurately before you blur anything.
- Apply the blur to the background only, and compare the result with the original.
The same sequence applies on a desktop editor with selection and mask tools: select the subject, refine the edge, then blur the background layer rather than the whole image. A desktop is the better choice for fine hair, glasses or busy edges, because a layer mask can be repainted at any stage without redoing the blur.
Web editors for a no-install fix
Web editors suit a single photo you want done quickly. Pixelcut identifies the background automatically and applies a Gaussian blur, and you drag a slider to the level you want. It accepts JPG, PNG and HEIC files up to 50MB and 6000 × 6000px, so a very large original may need resizing first.
Magic Studio supports JPG, JPEG, PNG, HEIC, WEBP and TIFF. If you dislike the automatic subject selection, you can refine it with an AI-assisted selection tool. Choose it when your file is WEBP or TIFF, or when the first automatic mask clips part of the subject.
The trade-off is control. A browser tool picks the edge for you, so it works best on photos with a clear separation between subject and background.
Making the blur look natural
Natural blur follows how real optics behave: backgrounds farther behind the subject look softer, and those close to it stay more readable. Magic Studio’s guidance matches this, suggesting a lower blur level for backgrounds closer to the subject and a higher one for backgrounds farther away. Apply that to the slider: a fence a short step behind a person should get less blur than a skyline in the distance.
- Keep the mask clean: a neater selection makes the blur look more realistic, so spend time on the outline before touching strength.
- Avoid maximum strength by default: a heavy blur on a background that sat close to the subject looks like a cutout.
- Reshoot when you can: getting closer to the subject makes the depth of field shallower, but too close and the camera cannot focus at all.
- Respect Portrait mode’s range: for iPhone Portrait shots, keep the subject between two and eight feet from the camera.
The distance and range guidance comes from iPhone Photography School.
Why distance and aperture shape background blur
Background blur is an optical effect before it is an editing effect. Research on simulating defocus renders it with a differentiable lens blur model, and an arXiv paper notes that higher f-stops reduce blur, producing an all-in-focus image at f/22 in its example. A Lens Blur style effect in an editor is aiming at that same look, so it convinces most when blur grows with distance from the subject instead of being applied evenly.
The payoff is separation. Cloudinary’s guide to image blurring describes a sharp subject against a blurry background as making the photo pop more. That also tells you when to leave a background alone: if it carries the story of the picture, softening it throws away the reason for the shot.
Saving and using the edited photo
Work on a copy and keep the untouched original, so you can return to it if a mask turns out badly. Once the edit looks right, you can move on to printing; How To Print Photos On Canvas: A Practical Step-By-Step Guide For Great Results In 2026 covers that next step.
Frequently asked questions
How do I blur a background after taking the photo?
It depends on the photo. A Portrait mode shot on a supported iPhone has a Depth slider. Anything else needs a subject selection in an editing app or a web tool that detects the background automatically before applying the blur.
Can I blur on iPhone after the shot?
Yes, if the photo was taken in Portrait mode on a model that supports the Depth slider. Older iPhones do not have it, so use an editing app with subject selection there.
How do I make blur look natural?
Match the strength to how far the background sat from the subject, with less blur when it was close. Also make sure the subject outline is accurately selected before you apply anything.
Does Portrait mode work in low light?
Not always. Portrait mode does not reliably produce the effect in dim conditions, so a photo taken that way may need the masking method instead.
