Line Art Maker converts your photos into artistic line drawings and coloring pages using a CoreImage filter pipeline. Grayscale, invert, Gaussian blur, and color dodge blend combine to extract clean outlines from any photo. Choose from five styles — Standard, Sepia, Blueprint, Blackboard, and Rainbow — and fine-tune line thickness and intensity with sliders. Long-press the image to compare with the original at any time.
Select any photo from your library and the app extracts its outlines using a four-stage CoreImage filter chain: grayscale conversion, color invert, Gaussian blur, and color dodge blend. The result is a clean line drawing that can be printed as a coloring page or used as art.
Standard produces a classic black-and-white line drawing. Sepia adds a warm brown tone with CISepiaTone. Blueprint maps the image to deep blue and white with CIFalseColor. Blackboard inverts the output for white lines on black. Rainbow composites a diagonal color gradient over the line art using Screen blend mode.
The Thickness slider controls the Gaussian blur radius (1–20) — higher values produce thicker, softer lines. The Intensity slider controls the contrast (0.5–3.0) — higher values produce darker, more defined lines. The image re-renders automatically when you release a slider.
Long-press anywhere on the image to instantly switch to the original photo. Release to return to the converted line art. The switch uses a smooth easeInOut animation so the comparison feels natural and non-disruptive.
CIColorControls desaturates the image to grayscale. CIColorInvert flips the brightness. CIGaussianBlur softens the inverted image — the blur radius is the Thickness parameter. CIColorDodgeBlendMode composites the blurred invert over the grayscale original, which produces bright areas where edges are strong and dark areas where they are absent. A second CIColorControls pass applies the Intensity contrast adjustment. All filter operations run on Task.detached to keep the UI responsive.
Standard outputs the line art as-is. Sepia applies CISepiaTone at full intensity for a warm antique look. Blueprint uses CIFalseColor to map darks to deep blue (0, 0, 0.6) and lights to near-white, producing a technical drawing effect. Blackboard applies a final CIColorInvert to produce white lines on black. Rainbow generates a diagonal seven-color gradient with CAGradientLayer and composites it onto the line art using CIScreenBlendMode, tinting the lines without losing the drawing structure.
An onLongPressGesture with a pressing closure drives an isShowingOriginal boolean. While the gesture is active the Image view renders the original UIImage; when released it switches back to the converted line art. Both transitions use .animation(.easeInOut(duration: 0.2)) for a smooth crossfade that makes before-and-after evaluation easy and natural.
Tapping the save button presents a rewarded ad via RewardedAdManager. After the ad completes and the reward callback fires, PhotoAlbumManager writes the converted image to PHPhotoLibrary inside an album named "My Line Art Studio", creating the album automatically if it does not yet exist. The save uses PHAssetCollectionChangeRequest to keep all converted images organized in one place.
Tap the Select Photo button on the home screen to open your photo library. Choose the photo you want to convert and the line art extraction starts automatically.
Select one of the five styles and use the Thickness and Intensity sliders to get the look you want. Long-press the image at any time to compare with the original photo.
Tap the save button and watch a short video ad. Once it finishes, your line art is saved to the "My Line Art Studio" album in your photo library — ready to print or share.
"I use this to turn photos of my kids into coloring pages and print them out. The thickness slider is great for making thicker lines that are easier for young children to color inside. The long-press comparison is a clever touch. Tried all five styles and they each work well for different types of photos."
"The Blueprint style is my favorite — architectural photos and landscapes come out looking genuinely impressive. Being able to fine-tune the line contrast with the Intensity slider makes a real difference. Watching an ad to save feels fair for a free app."
"Tried the Rainbow style on a flower photo and the result was beautiful. The app is straightforward — pick photo, adjust, save. The Blackboard style gives a very clean white-on-black look that works well for graphic subjects. Fun to experiment with different photos."
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