GIMP is a raster image editor for changing photographs, scanned artwork, interface graphics, and other pixel-based images. One document can hold several layers, selections, masks, text, paths, channels, and color adjustments. GIMP edits the working image and can export a flattened or transparency-aware result for another program. It does not organize a photo library, develop a video timeline, or preserve every editable layer when the user exports to an ordinary picture format.
XCF keeps the work
Save writes GIMP’s native XCF document. XCF retains layers, transparency, paths, channels, and other editing structure that a delivery format may not understand. The saved XCF is the file to reopen when further editing remains likely.
Export writes JPEG, PNG, TIFF, WebP, or another supported destination. Exporting does not make that destination the editable master. Closing after export can still trigger an unsaved-changes warning because GIMP tracks whether the XCF state itself has been saved.
Layers separate changes
Each layer carries its own pixels, position, opacity, and blend mode. The stack order decides which content appears in front. A transform can target the active layer, a selection, a path, or the whole image according to its tool setting.
Check the active item before painting or transforming. Editing the wrong layer can look like a failed command when another layer covers the result. Linked or grouped layers can also move together, so an unexpected shift may come from the selected transform target rather than damaged pixels.
Masks preserve pixels
A layer mask controls visibility with grayscale values. White reveals the layer, black hides it, and gray creates partial transparency. Painting the mask changes visibility without erasing the source pixels, which makes later correction possible.
The initial mask choice matters. Using a layer’s alpha channel copies its current transparency into the mask while leaving the original alpha in place. Transfer Alpha to Mask resets the layer alpha after moving that information. Choosing the wrong option can make transparent areas appear weaker because two transparency controls combine.
Selections have softness
The moving dashed boundary shows only one contour of a selection. Internally, GIMP stores the selection as a grayscale channel, so edge pixels can be partly selected. Feathering and Quick Mask expose that gradual boundary.
Quick Mask lets the user paint the selection itself. White adds selected pixels and black removes them. While that mode is active, some cut, paste, and paint actions affect the selection channel rather than the image. Leave Quick Mask before assuming that a brush has stopped painting color.
Filters need targets
Color commands and filters operate on the selected layer or layers and may limit their output to the current selection. Some filters retain editable settings in the layer workflow, while applying or merging results can make later separation harder.
A preview shows the current target, not every layer in the image. If only a small region changes, inspect the selection boundary. If nothing changes, confirm that the active layer contains pixels at that location and is not locked. Duplicate a source layer before a destructive edit that has no dependable later adjustment.
Color has profiles
GIMP can read an embedded image profile, use a monitor profile for display, and simulate another output profile through soft proofing. The file-open policy can keep the embedded profile or convert the image into the selected working space.
A screen preview depends on the correct monitor profile. Soft proofing estimates how another color space will behave, but the display settings do not control the separate print engine. Export the intended profile and test the receiving print workflow instead of treating one monitor view as proof of final paper color.
Canvas and layer differ
The image canvas defines the document boundary, while an individual layer can have a smaller or larger boundary. Scaling the image changes every layer and the canvas. Scaling one layer changes only that layer. Cropping can also target the image or selected layers.
This distinction explains why moved pixels can disappear beyond a layer edge or why transparent space remains after a crop. Use the command whose target matches the intended result. GIMP keeps the difference explicit because canvas geometry and layer geometry solve different editing problems.
Export loses structure
Every delivery format has limits. JPEG has no transparency and normally combines visible layers into one result. PNG can keep transparency but not GIMP’s full layer arrangement. Other formats may change color mode, metadata, or precision.
Review the export dialog rather than accepting an old preset blindly. Keep the XCF after delivery, open the exported file in another viewer, and check dimensions, transparency, profile, and compression artifacts. GIMP can produce the requested file only within the destination format’s own boundaries.
