Bokeh Effect: Turn Highlights Into Discs
A lens images an out-of-focus point as the shape of its aperture, which is why real bokeh is a disc with a defined edge. A blur cannot do that: it turns a point into a soft bell with no edge at all, and the difference is the whole effect.
Drop images here
or click to browse · or paste with Ctrl+V
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How far out of focus the background is. Every highlight becomes a disc this size.
Aperture shape
A lens images an out-of-focus point as the shape of its opening. Round is an expensive lens; five to eight blades is what most lenses actually have.
How bright a spot must be to form a disc. Low values turn the whole picture to soup; keep it high so only real highlights bloom.
Base blur softens everything that is not a highlight. Set it to zero to see the discs on their own.
Presets
Your photos are never uploaded. The disc scattering and the export both run inside this browser tab.
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Everything this tool does
Discs with an edge, not soft blobs
A bright point through the aperture kernel keeps 90 percent of its centre brightness at seventy percent of the radius, then drops to 0 just past the rim. Through a gaussian blur of the same radius it had already fallen to 48 percent, with no edge at all.
Real aperture shapes
Round, or five to eight blades as actual lenses have. A six blade kernel measured across a side against across a corner gives a width ratio of 0.85, against the 0.87 of a perfect hexagon, the difference being pixel rounding.
Brightness-weighted scattering
Brighter highlights carry more energy into their disc, which is why an out-of-focus streetlight is far brighter than a mildly light patch nearby rather than the same.
Screen blending
Overlapping discs are the normal case with fairy lights. Screen blending saturates them smoothly toward white instead of clipping them into flat patches as an additive blend would.
A threshold that matters
Bokeh appears only where something is genuinely much brighter than its surroundings. The threshold is what keeps the effect on real highlights instead of turning the whole picture to soup.
Separate base blur
Everything that is not a highlight is softened separately, which is what sells the idea that the camera was focused elsewhere. Set it to zero to see the discs alone.
Drag to compare
Before and after share one frame with a slider between them.
Six purpose-built presets
Classic round, six blade lens, very out of focus, subtle, obvious polygons and discs only.
Batch with one ZIP
Apply one lens character across a set and take everything as a single archive built in your browser.
Nothing is uploaded
No server, no queue, nothing to delete afterwards. Close the tab and every trace of the image goes with it.
What each control does
Disc size and shape describe the lens; the threshold decides what counts as a highlight worth blooming. Those three do almost all the work, and the base blur is what puts everything else out of focus behind them.
| Setting | What it does | Try | Watch for |
|---|---|---|---|
| Disc 6-12 | gentle, shallow blur | threshold 70+ | Subtle |
| Disc 20-40 | strongly out of focus | threshold 75+ | Slower to render |
| Round | an expensive lens | any | Very clean |
| 6 blades | what most lenses have | rotation 0-30 | The realistic choice |
| 5 or 7 blades | distinctly polygonal | any | Obvious shapes |
| Threshold 40-60 | many things bloom | intensity 40-60 | Turns to soup |
| Threshold 70-90 | only real highlights | intensity 60-90 | The right range |
5
aperture shapes
0
files uploaded
Screen
blend, only adds light
4-40
disc radius range
ZIP
batch download
Free
no account needed
FlipMyFormat vs other bokeh tools
| Capability | FlipMyFormat | Typical free tool |
|---|---|---|
| Files stay in your browser | ||
| Highlights become discs, not soft blobs | ||
| Real aperture shapes including blade counts | ||
| Brightness-weighted scattering | ||
| Screen blending, so discs only add light | ||
| Batch ZIP download without paying | ||
| No watermark on the output |
How to get bokeh that looks like a lens, not a blur
Bokeh is not blur, and the difference is easy to state. When a lens is focused elsewhere, a point of light in the background does not arrive at the sensor as a point; it arrives as a projection of the lens opening, which is why an out-of-focus streetlight photographs as a disc with a definite edge, and why a lens with six aperture blades gives you hexagons. Blur does something completely different: it averages each pixel with its neighbours, so a point of light becomes a soft mound that fades away with no edge anywhere. Put the two side by side and the blur reads immediately as software. That is why this tool scatters a shaped kernel from each bright pixel rather than averaging, and why the aperture shape is a control rather than a decoration. Getting a good result comes down to the threshold more than anything else. Bokeh in a real photograph appears only where something is genuinely much brighter than its surroundings, so if you set the threshold low, every mildly light area starts throwing discs and the picture turns to soup. Keep it high, around seventy to ninety, so only real highlights bloom. Then use the base blur to push everything else out of focus behind them, which is what sells the idea that the camera was focused somewhere else. Subject matters too: a photograph with no bright points in the background has nothing to make bokeh out of, and no setting will invent it.
- 1
Add a photo with bright points
Drag it in, click to browse, or paste with Ctrl+V. Fairy lights, street lamps, sun through leaves and water sparkle are what bokeh is made of.
- 2
Set the disc size and shape
Round is an expensive lens; six blades is what most lenses actually have. Then raise the threshold until only genuine highlights bloom.
- 3
Add base blur and export
The base blur puts everything that is not a highlight out of focus behind the discs. Set it to zero to see the discs on their own.
Why a disc is not a blurred point
A shape with an edge, not a bell
The distinction is measurable, and it is the clearest way to show why blur is not a substitute. We put a single bright pixel on black and rendered it both ways at the same radius. Through the aperture kernel, the resulting disc holds its brightness almost flat across its width and then falls off sharply: sampled at seventy percent of the radius it still had 90 percent of its centre value, and two pixels past the rim it was 0. Through a gaussian blur of the same radius, the same point became a bell whose value at seventy percent of the radius had already dropped to 48 percent of the centre, with no edge anywhere. That flat plateau with a sharp rim is exactly what your eye reads as an out-of-focus light, and it is the thing no amount of blurring will produce.
The aperture shape, and light that only adds
The kernel is built as a regular polygon of the blade count you choose, inscribed in the disc radius, so five blades gives pentagons and eight gives shapes close to circles, which is exactly how real lenses behave. We check the geometry: a six blade kernel measured across a flat side against across a corner gave a width ratio of 0.85, against the 0.87 a perfect regular hexagon would give, the difference being pixel rounding at this radius. Everything is then combined with screen blending, which can only ever brighten. That matters because overlapping discs are the normal case in a photograph of fairy lights, and an additive blend would push those overlaps out of range into flat white patches, while screen blending saturates smoothly toward white the way overlapping real highlights do.
What people use it for
Fairy lights and Christmas photos
The definitive bokeh subject. Strings of small bright lights turn into fields of discs.
Street scenes at night
Lamps, headlights and signs all become discs, which is the look night photography is known for.
Portraits with a busy background
Base blur plus discs pushes a distracting background back and makes the subject read.
Sun through foliage
Gaps between leaves act as bright points, which is where the loveliest natural bokeh comes from.
Water and reflections
Sparkle on water is thousands of small highlights, which is ideal material.
Product photography
A softly blurred background with a few discs makes a product look photographed rather than cut out.
Backgrounds for text
A bokeh field is a classic backdrop for titles and cards because it is busy without being distracting.
Wedding and event photos
Candles and string lights are everywhere at events and are exactly what this is for.
Six tips worth knowing
Keep the threshold high, around seventy to ninety. A low threshold makes everything bloom and the picture turns to soup.
Six blades is the realistic choice, because that is what most lenses actually have. Round reads as an expensive lens.
The photo needs bright points to work with. A background with no highlights has nothing to turn into discs.
Set the base blur to zero once, just to see what the discs alone are doing.
Larger discs need a higher threshold, since a big disc from a marginal highlight is very visible and looks wrong.
Rotate the aperture slightly with polygon shapes. Perfectly upright hexagons look synthetic.
Troubleshooting
The whole image turned to mush
Your threshold is too low, so everything is throwing discs. Raise it until only genuine highlights bloom.
Nothing happened
Your photo probably has no bright points in it. Bokeh is made from highlights, and no setting can invent them.
The discs look like flat white blobs
The intensity is high enough that overlapping discs are saturating. Lower it, or raise the threshold so fewer discs overlap.
It is slow on large images
Scattering a large kernel from every highlight is genuine work, and it grows with the square of the disc size. The preview uses a smaller copy so dragging stays responsive.
Frequently asked questions
What is bokeh?
The way a lens renders things that are out of focus. A point of light arrives at the sensor as a projection of the lens opening, so an out-of-focus streetlight photographs as a disc with a definite edge.
Why is blur not the same thing?
Blur averages each pixel with its neighbours, so a point becomes a soft mound that fades with no edge. A lens projects a shape. Put side by side, the blur reads immediately as software.
Can you show the difference in numbers?
We rendered a single bright pixel both ways at the same radius. The aperture disc still had 90 percent of its centre brightness at seventy percent of the radius and fell to 0 just past the rim; the gaussian blurred version had already dropped to 48 percent and had no edge at all.
Why do some photos have hexagonal bokeh?
Because the lens aperture is made of blades, and stopped down it forms a polygon rather than a circle. Six blades gives hexagons, and it is one of the easiest ways to tell what lens took a photo.
Which blade count should I choose?
Six is the realistic default, since that is what most lenses have. Round reads as an expensive lens with rounded blades. Five gives distinctly obvious pentagons.
What does the threshold do?
It decides how bright a spot must be before it forms a disc. Real bokeh appears only where something is much brighter than its surroundings, so keeping it high is what stops the whole picture blooming.
Why did my image turn to mush?
The threshold is too low, so every mildly light area is throwing a disc. Raise it to around seventy-five and only genuine highlights will bloom.
Why do brighter highlights make brighter discs?
Because they carry more light. The scattering is weighted by how far above the threshold each pixel is, which is why an out-of-focus streetlight is far brighter than a pale patch nearby.
What does screen blending do here?
It means a disc can only add light, never remove it, and overlapping discs saturate smoothly toward white. An additive blend would clip overlaps into flat white patches.
Nothing happened to my photo
It probably has no bright points. Bokeh is made from highlights, and if the background has none there is nothing to turn into discs.
What is the base blur for?
It softens everything that is not a highlight, which is what sells the idea that the camera was focused elsewhere. Set it to zero to see the discs on their own.
How is this different from tilt shift?
Tilt shift blurs according to position in the frame to fake a miniature. This creates aperture-shaped discs from highlights anywhere in the picture, which is what a shallow depth of field actually looks like.
Why is it slow on large images?
Scattering a kernel from every highlight grows with the square of the disc radius. The preview runs on a smaller copy so dragging stays responsive, and only the export processes at full size.
Which format should I export?
Keep the original for photographs. Bright discs against dark backgrounds are high contrast detail that JPEG rings around, so use quality 90 or above, or PNG.
Are my photos uploaded to a server?
No. The scattering and the export both run in your browser using the canvas API. Nothing is sent anywhere.
Is transparency preserved?
Yes for PNG and WebP output. The alpha channel is untouched. JPG has no alpha, so transparent areas are filled with the background colour first.
Can I process a batch?
Yes. Add as many photos as you like and the same disc size, shape and threshold are applied to each.
Does it add a watermark or need an account?
No to both. No sign-up, no email wall, no daily limit and no watermark on the output.