Image Size

[Malc@Portra.it]

I have a file with the following stats. Size 86m. Dimensions 6712 x 3380 pixels at 300dpi. How does Photoshop calculate the 86m size? Thanks in advance

[D.A.R]

If you have a file with those pixel dimensions you have a file that would print 56cm x 28cm.

Where are you getting the 86m from?

[gener7]

Pixel Dimensions 6712 x 3380 = 22,686,560  Total Pixel Count or TPC. Cameras go by this value.

22,686,560 TPC x 4 (the number of channels if it's in 8 bit CMYK mode.) = 90,746,240 binary MB /1048576 to get the value in decimal MB, 86.5 MB open file size that you see in the Image Size box.

RGB has 3 channels and so your file size would have been around 60 MB. That's how I figured it was a 4 channel file such as CMYK.

I should add that the PPI value is not relevant to the calculation. It is just metadata that will decide how large the image will be when printed on paper.

Also note that due to file compression when saving, the saved filesize value will be smaller on disk.

[JJMack]

86m what is M what size are you referring to.  If you want to know how mag bytes of Pixel data you have it would help to know the color depth you are editing in.  For a digital grayscale image there are 8bit per pixel.  One byte per pixel.  8Bit RGB Color 3Bytes per pixel,  16Bit Color 6 Bytes per pixel 32Bit color 12bytes per pixel.  Your image 6712px x 3380px  pixels equals 22,686,560MPx an 8bit rgb image with the many pixels would be 68,059,680MB uncompressed.    What size is 86m  what  units m is millions.

[Malc@Portra.it]

A big thanks to those who answered