cropped file size

i've taken image d700.

 

i've use lr crop @ ratio 3:1.

 

if open image in ps image dimensions 10.88 x 3.62. file size 2.48mb

 

if crop original (ok i've lightly cropped in lr first) in ps 36 x 12 file size 12.4 mb.

 

if crop lr cropped image from  10 x 3 31 x 12 file size same , cannot see discernable difference.

 

am losing here? concerned me image small compared original when intend print @ larger size.

 

is there setting in lr don't have correct or (i might answering own question here!) raw image has given number of pixels , cropping your're throwing number away , that's what's left!

 

how file bigger when re-sized in ps? worrying on nothing!

the term "crop" used rather broadly here imo - acknowledge in example above, ps had "re-sized" image version.

 

lr's "crop" tool just trims off parts of picture change composition. means see smaller number of original camera pixels inside new boundary, , number sets upper limit on quantity of true image detail can output. crop has no involvement in print size or resolution. when aspect ratio numbers such 16x12 (or whatever) appear in lr's crop tool, these guides use in order composition particular shape.

 

the time lr gives dimensions image (and linked that, pixels-per-inch resolution) when image exported, printed or published. if no particular dimensions given, same 1:1 screen view inside lr.

 

if lr output options state pixel width , height then gets made, resampling. in case whatever arbitrary resolution have entered, not materially affect file produced - still (say) 1600 x 1200 pixel jpg have asked for; regardless whether has been 'labelled' 12 ppi, 120ppi, or 1200 ppi figure.

 

if on other hand have stated inches width , height, resolution figure becomes crucial. given number of inches wide , high, fine resolution figure (lots of ppi) lead large filesize high pixel count, , coarse resolution figure (few ppi) lead small filesize low pixel count. available original pixel detail distributed across different numbers of new pixels in each case.

 

the same ideas apply photoshop crop tool too, except both changes composition trimming areas of picture away, and provides picture dimension options new trimmed composition fitted (these @ top of screen).

• the image can left original pixels (press "clear" button)
• it can reduced/increased different pixel numbers resampling (enter dimension in "px" (pixel) units);
• new inches dimensions resolution can entered (in case pixel numbers change suit)
• new inches dimensions can entered resolution left blank (in case pixel numbers stay same, , resolution figure adjusts suit).

 

the ps crop tool powerful if take close control on options; , bit of loose cannon imo if not. combines 2 rather unrelated functions, , convenient provided you know doing.

 

the important distinction in ps, these things happen working image. images inside lr cannot given dimensions described above (each 1 has number of original pixels avaiable inside current crop boundary, , that),

 

with lightroom image copy output, has pixel resampling, size, resolution, colourspace, use-specific properties imposed onto it.

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