Why are my TIFF files so large?

Question

My raw images after conversion to DNG in Lightroom Classic (LRC) are approx 100mb. After editing in Photoshop (PS) and saving the TIFF file grows to 2gb, even after flattening the images.

I have always used LRC but now ventured into PS but won't be able to continue this if the files are this size.

I suppose I have two questions for the forum. Firstly is this normal? Secondly is there another format I can try? I did try PSD but this is still 550mb?

Thanks

davescm · Answer

Yes it is normalThe DNG format contains the raw image, which from a camera is normally 3 greyscale files one for red data, one for blue data and one for green data. The red channel carries data for one quarter of the pixels in the image, the blue one quarter and the green a half. Each pixel is normally 14 bits and the file is then compressed using lossless compression. The TIFF file at 16 bit has two bytes for each colour channel at each pixel site. So 6 bytes for every pixel.  Unlike the raw (dng) file, Each channel red , green, blue has every pixel in the image. If you have more than one layer, then that increases the file size further. The file when saved may be compressed or not depending on your TIFF settings, but the files are always going to be larger than the raw files. My advice would be don't worry about file sizes, increase your storage if necessary. That way you can focus on the best image quality. The one exception is when sending a file onward, in which case you may need to export a copy and use a lossless lossy compression format (such as jpeg) but that should never be used for master files. Dave

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