Blog

How to check color differences after image conversion

Compare matching points in your original and converted images, read their color values, and tell normal compression changes from a conversion problem.

Rachel BennettTools and utilities Tools 4 min read

Colors can look different after you convert an image, even when the change is hard to spot. A format change, compression, or a color profile can affect what you see.

Use the Color Picker to sample matching areas and compare their displayed HEX and RGB values. This is a useful check, but it samples the color rendered on your screen, not the image file's stored pixel data.

Compare the same colors step by step

  1. Make a copy of the original image, then convert the copy. You can use the Image Converter to convert common formats such as JPG, PNG, WEBP, GIF, BMP, ICO, and TIFF. Keep the original unchanged.
  2. Open the original and converted images on the same computer and display. Keep their zoom and display size consistent. Chrome and Edge on a computer support the Color Picker's screen sampling; other browsers may offer a reduced version or none.
  3. Open the Color Picker and use its on-screen sampling control to choose a clear, flat-color area in the original. Note the HEX and RGB values it shows.
  4. Sample the matching area in the converted image. Choose the same point in the image, not simply a point with the same screen coordinates if the two images are displayed in different places.
  5. Repeat the comparison in several places. Check a flat color, a shadow, a highlight, and any area where the change is obvious. Write down each pair of values so you can compare them accurately.

If conversion changed the image dimensions or crop, match a recognizable feature instead of relying on the same pixel position. Avoid sampling an edge between two colors, where a small shift can put the pointer over a different part of the image.

What the color differences mean

The values match or are nearly the same

If several matching areas show the same or very close HEX and RGB values, the conversion probably preserved those colors in the areas you sampled. This does not prove that every pixel is identical, so check more points if color accuracy matters across the whole image.

Only a few values differ slightly

A small change in one or two RGB channels can be normal after a lossy conversion, such as saving a photograph as JPG. Compression approximates image data, and it can change colors slightly or create tiny variations around edges. The effect may be difficult to see even when the sampled numbers differ.

Many values differ, or a flat color changes noticeably

This may indicate a different color profile, a conversion setting, or that the images are being displayed differently. Check that you compared the same source image, the same region, and the same screen. If the change is visible across a large flat area, try converting another copy with a different format or quality setting.

The values look similar but the images look different

The Color Picker reports a screen-sampled color, and your display affects how that color appears. A changed color profile, display mode, or image viewer can alter the appearance. Also, a few samples cannot show changes in sharpness, banding, transparency, or fine details.

How to get a more reliable comparison

  1. Use the same source file. Convert a fresh copy of the original each time. Converting an already converted image can add further compression changes.
  2. Compare at the same size. Display both images at the same zoom and avoid stretching one to fit a different shape. Scaling can blend neighboring pixels and change the color that the picker samples.
  3. Sample flat areas first. Choose a region with one consistent color, away from text, borders, shadows, and gradients. Then check edges and detailed areas separately.
  4. Check the conversion format and quality. If the output is JPG, try a higher quality setting or a lossless format such as PNG when the goal is to preserve pixel colors. A larger file may be the tradeoff.
  5. Keep the display profile consistent. Do not change display color settings between samples. In Windows 11, check Settings › System › Display › Color profile. On macOS, check System Settings › Displays and the selected color profile. These settings can affect how colors look on screen.
  6. Check transparency separately. A transparent image can appear different over a colored background even when its visible pixels are unchanged. Compare both versions over the same plain background.

What the Color Picker can and cannot tell you

The Color Picker is useful for checking colors you can point to on screen. Its HEX and RGB readings let you compare samples without guessing by eye. For a fair comparison, view both versions in the same browser or image viewer, on the same display, with the same display settings.

Because the tool samples the rendered screen, it is not a file-analysis tool and does not calculate a whole-image difference score. A display profile or color-managed viewer may affect the displayed sample. If you need proof that file pixels are identical, use a pixel-by-pixel comparison method designed to inspect the image data, rather than relying only on a screen sample.

The Image Converter and Color Picker run in your browser, and the image files stay on your device.

More articles