Every dialog and its controls

Chapter 16 · Every dialog and its controls

Reviewed 4 November 2026 · Sources: Photopea learn documentation for image size, canvas size, adjustments, blur gallery, liquify, camera raw and preferences; in-application dialog inspection

Any menu item followed by an ellipsis opens a dialog, and in Photopea the dialogs are where the precision lives. A filter that looks like one click in the menu is usually a dialog with six controls, a preview toggle and a numeric field that accepts arithmetic. This chapter takes the dialogs one at a time and lists what is actually inside them: the fields, the sliders, the checkboxes, the preview behaviour and the keyboard conventions that apply across all of them. It is deliberately mechanical, because the value of a dialog inventory is that you can look up a control you half-remember and find out exactly what it does and where it sits.

Three conventions apply to nearly every dialog in the application and are worth stating once rather than repeating twenty times. First, almost every dialog has a Preview checkbox, and toggling it is the fastest way to judge an adjustment against the original rather than against the last state you saw. Second, numeric fields accept expressions: typing 50% or 120*2 into a width field evaluates rather than rejects, and the up and down arrow keys step a value while Shift plus an arrow steps by ten. Third, Alt turns the Cancel button into Reset in most adjustment dialogs, which restores every control to its default without closing the dialog — a behaviour carried over from Photoshop and one of the few places where the muscle memory transfers cleanly.

New Document

The New Document dialog is a single screen with a preset column on the left, a set of dimension fields in the middle and an advanced block underneath. The presets cover the usual print and screen sizes — A4, A3, Letter, 1920×1080, 1080×1080, 1080×1920 — and clicking one fills the fields rather than locking them, so you can start from a preset and then override the width. The fields are name, width, height, resolution in pixels per inch, colour mode, bit depth and background contents. Background contents offers White, Black, Transparent and Background Colour, and choosing Transparent is the only way to get an empty alpha channel at creation time; converting an existing white background to transparency afterwards is a separate operation that involves unlocking the layer.

One behaviour surprises people coming from desktop editors: Photopea caps new-document dimensions by available memory rather than by a fixed number, and very large documents at 16-bit will simply refuse to allocate. If a New Document dialog appears to accept a size and then produces a blank canvas, the allocation failed silently and the practical fix is to drop to 8-bit or reduce the dimension.

Image Size

Image Size is the resampling dialog. It shows pixel dimensions at the top, document size in physical units underneath, and a resolution field that links the two. The chain icon between width and height constrains the aspect ratio; clicking it off allows non-proportional scaling. The Resample checkbox decides whether pixels are interpolated or merely relabelled: with Resample on, changing the pixel dimensions adds or removes pixels using the interpolation method chosen in the dropdown; with Resample off, changing resolution alone leaves the pixel count untouched and only rewrites the metadata, which is the correct way to change print size without touching image quality.

The interpolation choice matters more than most users expect. Nearest Neighbour is the only method that preserves hard pixel edges and is therefore the correct choice for pixel art and for screenshots of UI; Bicubic Sharper is the right default for downscaling photographs; Bicubic Smoother is the right default for enlarging them. The two automatic variants pick between these based on whether you are scaling up or down, which is convenient but opaque — if you care about the result, choose explicitly.

Canvas Size

Canvas Size changes the document boundary without resampling anything. It shows the current size, the new size, and a nine-square anchor grid that decides which edge stays fixed. Choosing the centre anchor grows or crops symmetrically; choosing the top-left anchor keeps the top-left pixel in place and adds or removes from the right and bottom. The Relative checkbox switches the width and height fields from absolute to incremental, so you can type 200 with Relative on to add 200 pixels to the current width rather than setting it to 200. Canvas extension fills with the background colour, or with transparency if the layer is not a background layer.

Adjustment dialogs

The Image > Adjustments submenu is the densest collection of dialogs in the application. Most share the same skeleton — a histogram or gradient strip at the top, sliders underneath, a Preview checkbox and OK/Cancel — but the controls inside differ enough to justify listing them individually.

Levels

Levels is the tonal workhorse. It presents a histogram with three triangular handles underneath — black point, midtone gamma and white point — plus two output sliders that compress the result into a narrower range. The Channel dropdown switches between the composite and the individual colour channels, which is how you remove a colour cast by aligning the per-channel black points. Three eyedroppers sit to the right: set black point, set grey point and set white point. The grey-point eyedropper is the one that neutralises a cast in a single click, because it forces the sampled pixel to be neutral. The Auto button applies an automatic clip, and the Options sub-dialog behind it controls how much of the histogram tail is clipped, expressed as a percentage.

Curves

Curves replaces the three handles with a freeform line. The horizontal axis is input and the vertical axis is output, and clicking anywhere on the line adds a control point. Dragging a point up brightens that tone; dragging down darkens it. The steeper the segment, the more contrast in that tonal range; a segment that is nearly flat compresses that range into almost nothing. The dialog supports up to sixteen points, which is more than enough for any practical correction. Below the grid is a channel dropdown, three eyedroppers identical to Levels, and a pair of icons that switch between the freeform curve and a pencil mode that lets you draw the curve directly. The Auto button applies a contrast curve, and the Options sub-dialog controls the target colours and clipping percentages it uses.

The single most useful thing to know about Curves in Photopea is that the control points are keyboard-nudgeable: select a point and use the arrow keys to move it one unit, or Shift plus an arrow to move it ten. That turns curve editing from a mouse-accuracy exercise into a precise one, and it is the reason Curves is the adjustment professionals reach for first.

Hue/Saturation

Hue/Saturation has three sliders — Hue, Saturation and Lightness — and a dropdown at the top that switches the target between Master and the six colour ranges: Reds, Yellows, Greens, Cyans, Blues and Magentas. Choosing a colour range reveals two additional controls, a pair of range sliders that define the width of the affected hue band and the softness of its edges, plus three eyedroppers for picking a range from the canvas. The Colorize checkbox is the switch that converts the dialog from a relative adjustment into an absolute one: with Colorize on, the hue slider sets the hue of everything regardless of its original colour, which is how you tint a greyscale image.

Colour Balance

Colour Balance presents three sliders, each a pair of opposing colours: Cyan–Red, Magenta–Green and Yellow–Blue. A toggle above them selects whether the sliders affect Shadows, Midtones or Highlights, and the Preserve Luminosity checkbox keeps the brightness of the image constant while the colour shifts. Preserve Luminosity should stay on for photographic work; turning it off lets the adjustment change brightness as well, which is occasionally useful for stylised looks and usually a mistake otherwise.

Selective Color

Selective Color is the CMYK-minded adjustment. A dropdown selects a colour family — Reds, Yellows, Greens, Cyans, Blues, Magentas, Whites, Neutrals and Blacks — and four sliders adjust the cyan, magenta, yellow and black content of that family. The Relative and Absolute radio buttons decide whether the adjustment is a percentage of the existing ink or an absolute addition. This is the dialog to reach for when a single colour family needs to shift without disturbing anything else, and it is far more surgical than Hue/Saturation for that purpose.

Channel Mixer

Channel Mixer lets you build each output channel from a weighted sum of the input channels. The Output Channel dropdown selects Red, Green or Blue, and three sliders set how much of the red, green and blue input feeds that output. A constant slider adds a flat offset. The Monochrome checkbox collapses the three outputs into one and is the best black-and-white conversion method in the application, because it lets you choose exactly how much each colour channel contributes to the luminance rather than accepting a fixed weighting.

Gradient Map

Gradient Map maps luminance to a gradient. The dialog is essentially a gradient strip with a preset dropdown and the usual options for editing stops, plus Reverse, Dither and a Preview toggle. It is the fastest route to a duotone or a split-tone look: set a dark colour at the left stop, a light colour at the right, and every pixel is recoloured according to its brightness. Dither matters when the gradient is short and the image is 8-bit, because without it smooth tonal ramps can band.

Photo Filter

Photo Filter simulates a coloured filter over the lens. A Filter dropdown offers warming and cooling presets plus a custom colour swatch, a Density slider controls the strength, and Preserve Luminosity keeps brightness constant. The practical use is correcting a white-balance error that is too subtle for Camera Raw, or adding a deliberate warm cast to a scene that reads as cold.

Threshold and Posterize

Threshold is a single slider that converts the image to pure black and white at a chosen luminance cutoff — every pixel above the threshold becomes white, every pixel below becomes black. It is the correct tool for producing a bitmap mask from a continuous-tone image. Posterize is a single field that reduces the number of tonal levels per channel, producing flat bands; two to four levels give a screenprint look, and eight to sixteen give a subtle banding that can be useful as a stylistic base.

Shadows/Highlights

Shadows/Highlights is the recovery dialog. Two sliders, Amount and Tonal Width, control how much of the shadow or highlight range is lifted or pulled back and how wide that range is. A third pair, Radius, controls the local neighbourhood used to decide what counts as a shadow, which is what makes the adjustment local rather than global. The Color Correction slider sits between the two halves and adjusts saturation in the recovered areas, and a Midtone Contrast slider at the bottom restores punch that the recovery flattens. The Show More Options checkbox reveals the radius and colour controls; without it you only see the two amount sliders.

Exposure, Vibrance and Black & White

Exposure offers an Exposure slider measured in stops, an Offset slider that shifts the whole range, and a Gamma field that applies a midtone correction, plus three eyedroppers for setting black, grey and white. Vibrance is a two-slider dialog — Vibrance and Saturation — where Vibrance is deliberately non-linear and protects already-saturated colours, which is why it is the safer of the two for skin tones. Black & White offers six sliders, one per colour family, that control how much each colour contributes to the resulting grey, plus a Tint checkbox and hue/saturation pair for adding a tone back into the monochrome result.

The single-control adjustments

Several adjustments are a single control with no dialog worth describing at length, but they belong in a complete inventory. Invert flips every channel value with no options at all. Desaturate removes colour with no options. Equalize redistributes the histogram to use the full range automatically. Brightness/Contrast offers two sliders and a Use Legacy checkbox that switches between the old linear behaviour and the newer non-linear one. Replace Color combines a colour-range selection with hue, saturation and lightness sliders and a fuzziness control, which makes it a one-dialog version of select-then-adjust. Color Lookup applies a LUT file through a dropdown of built-in profiles and a Load button for a custom .cube or .3dl file.

Camera Raw

Camera Raw is the largest dialog in the application and the one most worth learning properly, because it is a non-destructive workspace rather than a single adjustment. The left side is a filmstrip of the open images; the right side is a stack of collapsible panels; the top is a toolbar with zoom, hand, white-balance eyedropper, crop, straighten and a before/after toggle. The panels are Basic, Tone Curve, Detail, Color Mixer, Color Grading, Optics, Geometry, Effects and Calibration, and each contains the controls you would expect from a desktop raw processor.

Two things distinguish Photopea's Camera Raw from the desktop original. The first is that it is available for any raster layer, not only for raw files, which makes it a general-purpose non-destructive grading environment rather than a raw-only stage. The second is that the changes are stored as a filter on the layer rather than baked into pixels, so you can reopen the dialog and adjust every value again at any time — the single most important architectural fact about the feature, and the reason it is worth using even for images that were never raw.

Blur Gallery

Blur Gallery is a single dialog that hosts five blur types, each with an on-canvas widget rather than a set of sliders alone. Field Blur places pins on the canvas, each with its own blur amount, and interpolates between them. Iris Blur places an elliptical region with four handles that control the focus ellipse, the feather and the falloff. Tilt-Shift places two parallel lines that define a sharp band with blurred regions either side. Path Blur draws a path and blurs along it, which produces motion blur that follows a curve. Spin Blur places a circular widget and blurs rotationally around its centre.

All five share a right-hand panel with Blur Tools (the type-specific amount), Blur Effects (bokeh, light bokeh, colour bokeh, highlights and a bokeh colour swatch), and a Noise tab for adding grain to the blurred areas so they match the grain of the sharp ones. The panel also carries a Preview checkbox and a Quality setting that trades render time for smoothness. The on-canvas widgets are the point of the feature: you position the blur spatially rather than describing it numerically, which is what makes a convincing depth-of-field effect possible in a browser.

Liquify

Liquify is a full-screen dialog with a toolbar down the left, a brush-size and pressure control across the top, and a right-hand panel of options. The tools are Forward Warp, which pushes pixels in the direction of the drag; Reconstruct, which unwinds the distortion progressively; Smooth, which averages neighbouring pixels; Twirl clockwise and counter-clockwise; Pucker and Bloat, which contract and expand around the brush; Push Left, which shifts pixels perpendicular to the drag; and Freeze Mask and Thaw Mask, which protect and unprotect regions so a warp does not spill into them. The right panel controls brush size, density, pressure, rate and turbulent jitter, and carries a Show Mesh checkbox and a Restore All button.

Liquify is one of the few dialogs in Photopea that is genuinely resolution-independent in feel: the brush size is expressed in pixels but the effect scales sensibly with zoom, so working at 100% and at 50% produces comparable results. The practical workflow is to freeze the features you want to keep — eyes, mouth, the edge of a jaw — before pushing anything, because reconstructing a spill after the fact is far harder than preventing it.

Vanishing Point

Vanishing Point is a perspective-aware clone and paste workspace. You draw a plane by placing four corner nodes on a surface, and the plane then defines a perspective grid. Anything cloned or pasted inside that plane is transformed to match the surface's perspective automatically, which is what makes it possible to paste a texture onto a wall or a floor and have it recede correctly. The dialog has a toolbar with Edit Plane, Create Plane, Marquee, Stamp, Brush, Eyedropper, Measure and Hand tools, plus a right-hand panel for plane settings and a flyout for the stamp's size, hardness and opacity. Multiple linked planes can be created so that a corner between two walls is handled as one continuous surface.

Select and Mask (Refine Edge)

The selection-refinement dialog is where a rough selection becomes a usable mask. It shows the image with a choice of view modes — marching ants, overlay, on black, on white, on a mask, and black and white — so you can judge the edge against the background it will actually sit on. The right-hand panel carries a Radius slider that expands the sampling area around the edge, a Smooth slider that rounds jagged edges, a Feather slider that softens the transition, a Contrast slider that hardens it, and a Shift Edge slider that moves the boundary inward or outward. A Decontaminate Colors checkbox removes the fringe of background colour that survives on semi-transparent edges, and an Output To dropdown decides whether the result becomes a selection, a layer mask, a new layer or a new document.

Layer Style dialogs

Double-clicking a layer opens the Layer Style dialog, which is a single window with a list of effects down the left and the controls for the selected effect on the right. The effects are Blending Options, Bevel & Emboss, Stroke, Inner Shadow, Inner Glow, Satin, Color Overlay, Gradient Overlay, Pattern Overlay, Outer Glow and Drop Shadow. Each effect has its own enable checkbox, so any combination can be active at once, and each has a blend-mode and opacity pair at the top of its panel. The dialog also carries a global blend mode and opacity for the layer itself in the Blending Options panel, plus Advanced Blending controls for fill opacity, channel checkboxes and a Knockout dropdown.

Layer styles are live and editable, which is the whole point: the dialog can be reopened indefinitely and every value re-tuned without touching pixels. They also export to PSD as editable effects, so a style built in Photopea survives a round trip to a desktop editor. The one limitation worth knowing is that styles apply to the layer's alpha channel, so a layer with soft edges produces a soft-edged stroke, which is usually correct but occasionally surprising.

Save for Web and Export

Save for Web is the export dialog, and it is the one dialog where the settings have a direct, measurable effect on the delivered file. The left side is a preview with a hand and zoom tool; the right side is a format selector with format-specific options; the bottom is a file-size readout and an estimated download time. The format dropdown offers GIF, JPEG, PNG-8, PNG-24, SVG, WebP and, where the browser supports it, AVIF. Each format reveals its own controls: JPEG gets a quality slider and a progressive checkbox; PNG-8 gets a colour-count field, a dither control and a transparency option; WebP gets a quality or lossless mode; GIF gets a colour table and an interlacing option.

The 2-up and 4-up tabs are the reason this dialog still earns its place: they show the original and the compressed version side by side at the same zoom, so quality loss is judged visually rather than guessed from a number. For a site like this one, where image weight is a real ranking factor, that comparison is worth the extra thirty seconds.

Color Range

Color Range builds a selection from colour similarity. A Select dropdown chooses between Sampled Colors, the six colour families, Skin Tones, and the tonal ranges Highlights, Midtones and Shadows. A Fuzziness slider controls how far from the sampled colour the selection reaches, and a Range slider narrows or widens the tonal window. Three eyedroppers — one to add, one to subtract, one for a range sample — let you build the selection incrementally, and a Selection Preview dropdown shows the result against the image in greyscale, black or white. Localized Color Clusters, when enabled, restricts the selection to spatially connected regions, which stops a skin-tone selection from also grabbing a similarly coloured wall across the frame.

Transform and Warp

Free Transform is not a dialog but a mode, and it deserves a place in a dialog inventory because its on-canvas controls are as structured as any panel. The bounding box has eight handles for scaling, corners for rotating when the cursor is outside the box, and a centre point that can be moved to change the pivot. The options bar carries fields for X, Y, width, height, rotation and skew, plus a chain for proportional scaling and a reference-point grid that decides which corner stays fixed. Right-clicking inside the box opens the full transform list: Scale, Rotate, Skew, Distort, Perspective and Warp.

Warp mode replaces the bounding box with a mesh. A grid dropdown selects the mesh density from 3×3 up to 10×10, and dragging any grid intersection bends the image locally. A Custom option lets you place and drag your own nodes. A Warp Text mode applies the same mesh to a text layer, which is the only way to curve type in Photopea without converting it to a shape. Holding Alt while dragging a node in Warp mode constrains the movement, and the Escape key cancels the whole transform while Enter commits it — the two keys worth memorising.

Preferences

Preferences is reached from Edit > Preferences and is a multi-tab dialog rather than a single screen. The tabs cover General, Interface, Performance, History, Plugins and Advanced. General holds the colour picker style, the interpolation default, the ruler unit and the option to use a legacy undo model. Interface controls the theme — dark or light — and the UI scale. Performance holds the memory and cache settings, including the scratch space that determines how large a document the application can handle. History holds the number of undo states retained, which is the single setting most likely to affect how comfortable the application feels. Plugins holds the endpoint configuration for the plugin system described in chapter 15. Advanced holds developer-facing toggles and a reset button that restores every preference to its default.

The history setting deserves emphasis because it is the one preference that changes how you work rather than how the application looks. Photopea defaults to a modest number of states, and raising it costs memory but buys the freedom to experiment. If you find yourself hesitating before a destructive operation, the fix is usually to raise the history limit rather than to become more careful.

What the dialog inventory reveals

Reading the dialogs as a set rather than one at a time produces an observation that the individual descriptions hide: Photopea's dialog coverage is uneven in a specific and predictable way. The dialogs that correspond to core raster editing — Levels, Curves, Hue/Saturation, Camera Raw, Blur Gallery, Liquify, Layer Style — are complete and in several cases better than their desktop equivalents because they are non-destructive. The dialogs that correspond to print production — soft proofing, output intent, trap, separation preview — are absent entirely. The dialogs that correspond to motion and 3D are absent. This is not a random set of gaps; it is the profile of a tool built for screen output and web delivery, and it is consistent with the limitations documented in chapter 19.

The practical consequence is that the dialog inventory doubles as a capability map. If a task can be expressed as a raster adjustment, a spatial blur, a warp, a layer effect or an export setting, there is a dialog for it and it is probably good. If a task requires a printing-press workflow, a timeline or a 3D scene, there is no dialog and no amount of menu exploration will find one. Knowing which of those two categories a task falls into before you start is worth more than knowing any individual slider.

Chapter 17 takes the same item-by-item approach to the Filter menu, where the dialogs are numerous enough to need their own alphabetical catalogue.