The Canon TS 6520 does not render text through its app; the app is a control and scan bridge, and the distorted words you see on your computer screen are produced by your computer's graphics stack, the app's preview renderer, or a mismatched scan or print setting. In most cases the distortion is a display or preview artifact, not a defect in the printer's physical printing mechanism, and it clears when you fix resolution, color, or driver settings.
This explainer separates the three places distortion can enter the pipeline: the app's on-screen preview, the scanned image the app hands to your computer, and the print job your computer sends to the printer. Each has a different cause and a different fix. Reading the symptom correctly is most of the repair.
The rendering pipeline behind the app screen
The Canon TS 6520 is an inkjet multifunction device. Its job is to place ink dots on paper and to move a scan head across a document. Neither of those operations produces the pixels you see on your monitor. Your computer's operating system composes the window, the app draws the preview, and the graphics driver rasterizes text.
Text on a screen is stored as glyph outlines and rendered at the screen's pixel grid. When the app asks for a preview, it may downsample a high-resolution scan to fit the window. Downsampling text without proper filtering produces aliasing: thin strokes break into stair-steps and small letters blur. That is a preview artifact, and it disappears at 100 percent zoom or when you export the file at full resolution.
The scan path adds its own distortion. A flatbed scan at low resolution, say 75 dots per inch, cannot capture the edges of 8-point text. The scanner samples the page on a grid, and any stroke narrower than the sample spacing is averaged into the background. The resulting file looks soft or broken, and the app faithfully displays that soft file. The printer did not distort anything; the sampling did.
The print path is separate again. When you print from the app, the computer sends a page description to the driver, which rasterizes it at the printer's native dot grid. If the driver substitutes a font or the app sends a low-resolution image instead of text, the printed page can look wrong even though the screen preview looked fine. Screen and print are two different renderings of the same document, and they can fail independently.
Plain language: the app is a window, not an artist. What you see depends on the file it was handed and how your computer draws it.
Quantified context: resolution, scaling, and where text breaks
Resolution thresholds explain most distortion. A typical monitor shows about 96 pixels per inch at standard scaling. Text rendered below roughly 8 pixels of cap height loses its stroke detail. At 125 percent or 150 percent display scaling, the operating system re-renders glyphs at a different pixel grid, and apps that cache bitmaps instead of re-rendering can show blurry or jagged text.
Scan resolution matters more than most users expect. Text is legible in a scan at 200 to 300 dots per inch. Below about 150 dots per inch, 10-point text starts to smear. A 75-dot-per-inch scan of a full letter page produces roughly 637 by 825 pixels, which is smaller than many phone screens and far too coarse for small type.
Color settings distort perceived sharpness. A scan saved in a heavily compressed JPEG format at low quality shows blocky artifacts around letters, especially dark text on white. The 8-by-8-pixel compression blocks create ringing and smear at edges. Saving as PNG or a high-quality JPEG removes that class of artifact entirely.
Monitor settings contribute. A non-native resolution, such as 1366 by 768 stretched onto a 1920 by 1080 panel, resamples every pixel and softens all text. So does a sharpness setting turned too high on the monitor itself, which adds halos around letters.
Edge cases that mimic printer distortion
Several conditions look like app distortion but originate elsewhere. A failing ink cartridge causes banding on the printed page, and a user who scans that page back through the app sees the banding as distortion. The printer is the source, but the mechanism is nozzle clogging, not rendering.
A scan of a curved or folded page produces warped lines because the scan head's depth of field is shallow. The app shows the warp honestly. Similarly, scanning through a dirty platen glass adds streaks that read as text distortion.
Font substitution is a common edge case. If the app or driver cannot find the document's font, it substitutes a metrically different one, and line breaks shift. On screen the text looks cramped or overlapping. This is a font availability problem, not a graphics defect.
Wireless interference can corrupt a print job mid-transfer, producing garbled characters on paper. On screen, a corrupted preview can occur if the app streams a partial scan over a weak Wi-Fi link. The Canon TS 6520 supports wireless printing, and a weak 2.4-gigahertz signal is the usual culprit.
Driver mismatches are frequent. Installing a generic driver instead of the model-specific Canon driver can cause the app to request a page format the driver renders poorly, producing fuzzy or misaligned previews.
Misconceptions about app-side distortion
The most common misconception is that the printer renders the screen. It does not. The printer receives a rasterized page or a scan command; it never drives your monitor. Any distortion visible only on screen is a computer-side problem.
A second misconception is that reinstalling the app fixes rendering. The app is a thin client. Reinstalling it may reset preferences, but it does not change how the operating system rasterizes text or how the scanner samples the page.
A third is that higher scan resolution always looks better in the preview. Very high resolution scans, such as 1200 dots per inch, produce large files that the app downsamples aggressively for display, and the downsampling itself can look worse than a moderate-resolution scan shown at native size.
A counterintuitive detail: a sharper monitor can make distortion more visible. High-density displays render preview thumbnails at small physical sizes, and the app's crude downsampling shows more clearly against a crisp background. The distortion was always there; the better screen simply reveals it.
Professionals treat the preview as a thumbnail, not a proof. They export at full resolution and inspect the file in an image editor before judging quality.
Comparison of distortion sources and fixes
| Symptom | Likely source | Mechanism | Fix |
|---|---|---|---|
| Jagged or stair-stepped letters on screen | Preview downsampling | Aliasing from crude scaling | Zoom to 100 percent or export full resolution |
| Soft, smeared text in scanned file | Low scan resolution | Sampling below stroke width | Rescan at 200–300 dots per inch |
| Blocky artifacts around letters | JPEG compression | 8-by-8 block quantization | Save as PNG or high-quality JPEG |
| Cramped or overlapping lines | Font substitution | Missing font replaced by different metrics | Install the document font or embed fonts |
| Garbled characters on printed page | Corrupted print job | Wireless transfer error | Reprint over USB or a stronger signal |
| Banded or streaked output | Clogged nozzles or dirty glass | Ink delivery or optical obstruction | Run nozzle check and clean platen |
Timeline: from scan to screen
| Stage | Time scale | What happens | Distortion risk |
|---|---|---|---|
| Scan capture | 5–30 seconds per page | Scan head samples the page | Low resolution, dirty glass |
| App transfer | Under 1 second on USB, 1–10 seconds on Wi-Fi | Image moves to computer | Partial transfer on weak signal |
| App preview render | Milliseconds | Downsample to window size | Aliasing, blur |
| Operating system compositing | Milliseconds | Window drawn at display scaling | Scaling blur, non-native resolution |
| Export or print | 1–60 seconds | File saved or job rasterized | Compression, font substitution, driver mismatch |
The timeline shows that distortion can be introduced at four separate stages, and the stage determines the fix. A user who blames the printer for a preview artifact will waste time cleaning nozzles that are working fine.
Practical actions and thresholds
Work through these steps in order, because each one isolates a different stage.
Confirm the screen symptom at 100 percent zoom. If the text is sharp at full size, the distortion is preview downsampling and needs no repair. Rescan any suspect document at 300 dots per inch and save as PNG. Compare the exported file in an image editor, not the app preview. Check display scaling in the operating system settings. Set it to 100 percent temporarily to see whether scaling caused the blur. Verify you installed the model-specific Canon driver for the TS 6520, not a generic one. Run the printer's nozzle check pattern. If the pattern is clean, the print mechanism is not the source. For wireless garbling, switch to a USB connection for one test print to isolate the network.
Thresholds worth remembering: 150 dots per inch is the floor for legible small text, 300 is the working standard for documents, and anything below 8 pixels of cap height on screen will look rough regardless of source quality. If a scan is below 150 dots per inch and the text is small, rescan rather than adjust the display.
Limitations and what this cannot settle
This explainer covers the stable mechanisms of rendering and scanning. It cannot diagnose a specific unit without inspection. A failing scan head, a worn cartridge, or a hardware fault in the printer can produce symptoms that overlap with software distortion, and only a service technician can confirm those.
Firmware and app versions change, and menu names differ between operating system releases. The principles here hold, but exact settings paths vary. Where a manufacturer's documentation conflicts with this explanation, follow the documentation for your specific firmware version.
No single fix applies to every case. Isolate the stage first, then apply the matching remedy. If distortion persists at full-resolution export with a model-specific driver and a clean nozzle check, the remaining suspect is hardware, and that requires professional service.