#4. Why does image file format matters?
This post is part of a weekly series about image screening. All published posts can be found on this page.
One component of the production process at many journals is to screen all images to confirm that they are of sufficient resolution for publication and to ensure that they have not been altered in any way that could impact the paper’s conclusions. We’ve discussed the importance of figure and image resolution. Part of ensuring the appropriate resolution when acquiring images lies in checking the settings on your imager and/or scanner. The second, equally important part comes when you are ready to export a gel image to a non-proprietary file type. Which one to choose? JPEG? TIFF? BMP? PNG?
JPEG or JPG (short for Joint Photographic Experts Group) is a compression technique that reduces file size and is therefore widely used for large image files. However, it is “lossy”, which means that some amount of data is lost in the compression process. In contrast, TIFF/TIF (tagged image file format) is a lossless format that, unlike JPEG, allows you to edit and re-save the file without any loss in image quality. We therefore wholeheartedly encourage you to use TIFF only. Both JPEG and TIFF are widely supported formats, so you should be able to obtain these files from scanners and digital imagers and to open them with your figure-making software. If for any reason your data has to be acquired in a JPEG or any other non-TIFF format such as BMP, one way to avoid future loss of resolution is to open it immediately (in Photoshop for instance) and save or export the image as a TIFF.
Now that you have high-resolution image data properly stored as TIFFs, it is time to start making figures (and to write the actual paper! And do more experiments! And draft this grant/fellowship application!)