Clearer images

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We have discovered a way to print images more faithfully, especially banding patterns of proteins (or nucleic acids) that have been separated and subsequently visualised. To scan in black and white and then print in colour might seem counterintuitive, but the final results (figure) clearly show improved discrimination of individual bands and a less grainy background.The explanation is readily understandable in that the algorithm (called “dithering” in the print trade) for conversion of individual values on the greyscale will be governed primarily by the distance between contiguous pixels rather than the much higher resolution of the printer (eg, 1200 dots per inch [dpi]). This effect is readily seen in the figure, in which even at 760 dpi there are course, grainy pixels that are widely spaced and represent the low degree of diffuse background staining on the white nitrocellulose membrane.In principle, a black and white laser printer can only print or not print each black dot, rather than printing a grey dot. However, a colour printer can mix various lighter and darker hues to produce different degrees of grey. On careful examination a slightly green-blue colour cast, rather than a strictly black and white image, can be seen.This trick will faithfully print bands, for example, for western, northern, or Southern blots, for more accurate representation of any image. The final print also looks sufficiently black and white to be accepted or scanned by non-electronic journals and avoid colour printing. This result is a clear improvement on black and white laser prints. We have discovered a way to print images more faithfully, especially banding patterns of proteins (or nucleic acids) that have been separated and subsequently visualised. To scan in black and white and then print in colour might seem counterintuitive, but the final results (figure) clearly show improved discrimination of individual bands and a less grainy background. The explanation is readily understandable in that the algorithm (called “dithering” in the print trade) for conversion of individual values on the greyscale will be governed primarily by the distance between contiguous pixels rather than the much higher resolution of the printer (eg, 1200 dots per inch [dpi]). This effect is readily seen in the figure, in which even at 760 dpi there are course, grainy pixels that are widely spaced and represent the low degree of diffuse background staining on the white nitrocellulose membrane. In principle, a black and white laser printer can only print or not print each black dot, rather than printing a grey dot. However, a colour printer can mix various lighter and darker hues to produce different degrees of grey. On careful examination a slightly green-blue colour cast, rather than a strictly black and white image, can be seen. This trick will faithfully print bands, for example, for western, northern, or Southern blots, for more accurate representation of any image. The final print also looks sufficiently black and white to be accepted or scanned by non-electronic journals and avoid colour printing. This result is a clear improvement on black and white laser prints.