We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
JPEG signal to noise ratio
This graph demonstrates one of the benefits of restricting the Pentax K-500's pixel count to 16 million as it produces cleaner images than most of the competing cameras at the low to mid sensitivity range. Its score drops off considerably at the highest settings, however, when noise becomes a much more significant issue.
Raw (converted to TIFF) signal to noise ratio
The raw file (after conversion to TIFF) results suggest that Canon and Nikon are prepared to mask more detail in an effort to hide noise in the JPEG files than Pentax. The results are good at the lower sensitivity settings, but the Canon 100D produces cleaner images from about ISO 400 and above. The Nikon D3200, which has a pixel count of 24 million also outperforms the K-500 in the low to upper-middle sensitivity range.
JPEG dynamic range
JPEG dynamic range figures tend to reflect the level of contrast that manufacturers want to give the images that their cameras produce. The Canon 100D and Pentax K-500 both produce quite punchy images with a pleasant level of contrast, whereas the Nikon D3200's JPEGs exhibit greater tonal range.
Raw (converted to TIFF) dynamic range
Raw file dynamic range values give a better indication of a cameras ability to record different brightnesses in a single image. After conversion to TIFF the Pentax raw files have a very impressive dynamic range at the lowest sensitivity, beating the rest of the competition, but it dips quite sharply so that it is the lowest for most of the sensitivity range.