Why Your PNG to SVG Conversion Doesn't Look Like the Original

A PNG to SVG conversion rarely looks identical to the original because converting is not copying: the software has to turn a grid of coloured pixels into shapes and curves, and every step of that translation simplifies something. Most differences come from five causes, and some of them you can fix.

You expected the SVG to be the PNG, only sharper. Instead the colours shifted, a thin line vanished or the edges look slightly wrong. This is normal, and it is not a sign that you did something wrong. This guide explains where the drift comes from and what to do about it. For the general method, see our guide to converting a PNG logo to SVG, and for the first diagnosis, why a vectorized SVG loses detail.

Why can a PNG never be copied exactly into an SVG?

A PNG stores every pixel. An SVG stores no pixels: it stores mathematical shapes, with a fill colour and an outline made of curves. To go from one to the other, a tracing algorithm groups similar pixels into zones, follows their boundaries and fits curves to them within a tolerance. The result is an approximation by design, and the tolerance decides how close it gets.

Tutorials for converting a PNG to SVG with Inkscape say the same thing in practice: the quality of the input matters, and complex or very small images give poor results. That is the algorithm working as designed, not a bug.

What are the five most common causes of drift?

• Colour reduction. The tracer merges similar shades into a limited palette. Subtle gradients become flat zones or visible bands, and a colour can shift slightly to the nearest palette entry.
• Smoothing of edges. Curves are fitted through the pixel boundary, so jagged edges become smooth, and tiny irregularities that were part of the design disappear.
• Loss of small features. Details smaller than the tolerance are treated as noise. Thin strokes, small counters in letters and fine dots are the usual victims.
• Rounded corners. A fitting algorithm can read a sharp corner as a curve, so it softens points that should stay crisp.
• A low-resolution source. If the PNG is small or compressed, the pixels already contain artefacts, and the tracer faithfully traces the dust and blur.

Which of these can you fix, and how?

Start with the source. A larger, cleaner PNG with fewer compression artefacts always traces better. Then match the preset to the image: flat colours for logos, a detailed mode for photos and gradients, black and white for line art. Raising the colour count helps gradients but makes the file heavier.

What global settings cannot fix is a local defect, such as a single thin letter that merged or a small counter that filled in. Raising the precision for that one spot degrades the rest of the file. Repairing only the damaged zone is the clean answer, and we describe the method in how to fix an SVG after automatic vectorization.

How do you measure the drift instead of guessing?

Compare the SVG and the PNG at the same zoom and flick between them. Or use a tool that does the comparison for you. VectoFix re-renders the SVG, compares it with your PNG and gives a fidelity score out of 100 with a red map of the gaps. Some images, such as painted renderings, gradients everywhere and photos, degrade uniformly, and the whole map turns red. That is not a fault of the tool: those images are simply a poor match for vectorization, and a raster format may suit them better. Our article on SVG versus PNG helps you decide.

When should you accept the difference?

If the SVG will be printed large, cut, embroidered or scaled, a small colour shift matters less than clean, scalable outlines, and the trade is worth it. If exact colour or photographic detail is the point, keep the PNG, or use the SVG only for the parts that are real shapes. Printers have their own reasons for preferring vectors, explained in why printers ask for vector files.

Conclusion: expect an approximation, then improve it where it counts

A converted SVG is an approximation, so judge it by the zones that matter for your use. Improve the source, pick the right preset, and repair what is still wrong locally. VectoFix shows the damage map and lets you paint over the problem, with 3 full-resolution HD exports to try and a Pro licence at a one-time €39.