Image Quality

The visual fidelity of an image — determined by resolution, compression level, format choice, and capture conditions — which affects how sharp, detailed, and accurate the image appears.

What determines image quality

Image quality is not a single property but an interplay of several factors that together determine how an image looks to the viewer.

Resolution defines how many pixels the image contains. A 3840x2160 screenshot contains four times as many pixels as a 1920x1080 capture of the same content. More pixels mean finer detail, sharper text, and smoother curves. On high-DPI displays, low-resolution images appear visibly soft or pixelated.

Compression affects quality by determining how much data is preserved. Lossless compression (PNG, WebP lossless) preserves every pixel exactly. Lossy compression (JPG, WebP lossy, AVIF) discards data to reduce file size — the amount discarded is controlled by the quality setting. Higher quality retains more data; lower quality discards more.

Format choice matters because different formats handle different content types with varying effectiveness. JPG's block-based compression produces artifacts around sharp edges, making it a poor choice for screenshots with text. PNG preserves these edges perfectly but produces larger files for photographic content.

Capture conditions include the screen resolution at the time of capture, the pixel density of the display, and whether the capture tool is rendering at native or scaled resolution. A screenshot taken on a Retina display at 2x density captures twice the detail in each dimension compared to a standard display.

Quality vs file size tradeoff

Quality and file size are inversely related in lossy formats. Every reduction in file size comes at the cost of some visual information.

This tradeoff follows a curve of diminishing returns in both directions. Reducing quality from 100% to 90% dramatically shrinks file size with almost no visible change. Reducing from 90% to 80% provides meaningful size savings with minimal perceptible loss. Below 70%, artifacts become increasingly obvious — blurred text, blocky gradients, and ringing around edges.

For screenshots specifically, this curve is steeper than for photographs. Text and UI edges are highly sensitive to compression artifacts because the human eye is extremely good at detecting irregularities in straight lines and character shapes. A quality setting that looks fine for a landscape photo may make a screenshot's text noticeably degraded.

The practical implication is that screenshots demand either lossless compression or very high lossy quality settings, while photographic content can tolerate lower settings without visible degradation. Workflows that handle both types of content benefit from tools that let you set quality per image or per content type rather than applying a single global setting.

Quality settings in export

Export quality settings control the compression aggressiveness applied when saving an image. Understanding these settings prevents unnecessary quality loss and file bloat.

For lossy formats, quality is typically expressed as a percentage or a 1-100 scale. This number does not mean "90% of the original quality" — it represents a compression parameter that influences how much data the algorithm retains. The relationship between this number and perceived quality varies by format and content.

For lossless formats, there is no quality setting because all data is preserved. However, there is a compression level that affects encoding time. Higher PNG compression levels produce slightly smaller files but take longer to save. The visual result is identical regardless of compression level.

Some capture and export tools offer format-aware quality presets — automatically applying lossless encoding for screenshot content and lossy encoding for photographic content. This removes the guesswork and ensures appropriate settings without manual adjustment.

When exporting for multiple destinations, consider the downstream processing. Images uploaded to social media or messaging platforms will be re-compressed, so starting with higher quality provides headroom for this second round of compression.

The operational win is to treat quality as destination-specific. Keep the cleanest practical master, then export smaller derivatives for social, docs, or previews instead of reusing one compromised file everywhere.

Common mistakes

• Using JPG for text-heavy screenshots. JPG's lossy compression introduces artifacts around sharp text edges, reducing readability. Use PNG or WebP lossless for screenshots where text matters.
• Assuming higher quality settings always produce better results. Above 90-95% in lossy formats, file sizes balloon with negligible visual improvement. Find the threshold where quality is indistinguishable from lossless.
• Capturing at low resolution and scaling up. Enlarging a low-resolution screenshot cannot add detail that was never captured. Always capture at the highest available resolution and scale down if needed.
• Ignoring display density when capturing. A screenshot taken at 1x resolution looks soft on a 2x Retina display. Capture at native display density to ensure the screenshot looks sharp on the target viewing device.