A maths question

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Simpo Two

Original Poster:

85,147 posts

264 months

Saturday 18th October 2014
quotequote all
This will entertain the more tecchy readers.

Yesterday I took a JPG image measuring 2560 x 1920 pixels and 2.5Mb in filesize, opened it in PS and went to crop it to 1500px longest side.

In just a few seconds my computer filled all available space (about 200Gb) with temp files and locked up. I'd set it to 1500" not pixels banghead

What size file was it trying to make?

marshalla

15,902 posts

200 months

Saturday 18th October 2014
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Which resolution (dpi/ppi) and which compression/quality factor had you selected ?

GetCarter

29,358 posts

278 months

Saturday 18th October 2014
quotequote all
Simpo Two said:
What size file was it trying to make?
A shed load.

Simpo Two

Original Poster:

85,147 posts

264 months

Saturday 18th October 2014
quotequote all
marshalla said:
Which resolution (dpi/ppi) and which compression/quality factor had you selected ?
The original file appeared as 180ppi; no further compression at that stage as I never got as far as 'save'!

mike80

2,248 posts

215 months

Saturday 18th October 2014
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I don't know, but I remember doing something similar a few times and not figuring out what was going on... A lot of wasted time!

DIW35

4,145 posts

199 months

Saturday 18th October 2014
quotequote all
Assuming it was using 180 ppi you mentioned, and maintaining the same aspect ratio of the original, the resulting image of 1500" x 1125" would have been 270,000 x 202,500 pixels. File size would depend on compression and quality setting used.

Geordie MGmike

134 posts

138 months

Saturday 18th October 2014
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550Gby if your disc is big enough biglaugh

crmcatee

5,691 posts

226 months

Saturday 18th October 2014
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Tried to do that a few times - now I just click on the action I created and know it's set to pix and not inch smile

RobDickinson

31,343 posts

253 months

Saturday 18th October 2014
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Note file size on disk is compressed ( jpg or psd etc). File size in photoshop is not compressed, its the equivalent of bitmap , it tells you how big a file is in the status bar at the bottom ( well how much memory being used). A 20mp ~23meg raw file I have open (and nothing else, layers etc) is using 110meg of memory

Simpo Two

Original Poster:

85,147 posts

264 months

Saturday 18th October 2014
quotequote all
Ah, a bitmap 125 feet long - yep, that would account for my hard drives being filled with the computing equivalent of expanding foam!

RobDickinson

31,343 posts

253 months

Sunday 19th October 2014
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By my calculation a 270,000 x 202,500 image at 16bit would be about 30gb image size..

LongQ

13,864 posts

232 months

Monday 20th October 2014
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Simpo Two said:
In just a few seconds my computer filled all available space (about 200Gb) with temp files and locked up. I'd set it to 1500" not pixels banghead
You need a slower computer. One that would take a few hours to fill the disk and so give you time to realise there might be a mistake and kill the process.

I have a couple I could offer if you are interested ....