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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?
Yes it is normal
The 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.
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 compression format (such as jpeg) but that should never be used for master files.
Please forgive the nitpicking but you may have mistyped (»lossless« instead of »lossy«).
I also seem to dimly remember an issue where some compression would work less well (possibly to the point of increasing file-size) in 16bit – was it LZW maybe?
That's right. LZW is for 8 bit data, and it can actually increase the size of 16 bit TIFFs.
There's one more thing with compression: it can be computationally intensive and drastically increase open and save times. In many situations that's much more important than the resulting file sizes. As Dave says - don't worry about it, get more disks. Image files will be big and take up a lot of space, and sooner or later you will run out. Better to have a long term strategy for it, than trying to postpone the inevitable by compression.
Blimey - so I did - I'll correct it. Thanks
Thanks Dave, I understand now.
I suppose my workflow will be that my really important photos that I have invested a lot of time in PS will become TIFF and the remainder remain as DNG.
The 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.
Yes, except that the raw file is one single channel. The demosaicing into R, G and B components isn't in the file - it's in the raw processor, knowing the layout of the Bayer filter array in front of the camera sensor.
Yeah, even more nitpicking 😉
True - but I was just trying to get the concept over that the raw file does not contain full colour info for every pixel.
But nitpicking can be good and useful 😉
I know you know. But I can be pedantic with the best of them 😄