Need help again, this time with file size

[jennifer_arneson]

Hello everyone,

 

sorry to bother you with my stupid questions again but I have another problem

now. I was asked to provide some photos with 300 dpi for prints and so I

changed the ppi from 72 to 300 in Photoshop only to find out that the

resulting copy has a way smaller file size than the original picture. For

example, my original jpeg with 3500x2300 resolution and 72 ppi has a file size

of 3 MB and the 300 ppi copy has 800 KB. Will the smaller file size affect the

quality of the print? I'm guessing yes. I just don't understand why the file

size should be affected since the pixels remain the same and the ppi is only

relevant for the prints

 

Apart from changing the ppi, I only experimented with Levels and Contrast-

does this affect the file size also? Is there a way I can increase the file

size back to the original or at least 2/3rds?

 

And one last question- in Photoshop Preferences, under Units and Rulers, I see

that in "New Documents Preset Resolutions", print resolution is set to 300 ppi

and screen resolution to 72 ppi. When I send the photos, will these setting be

the same ( meaning I don't have to worry about manually changing the ppi for

each photo) or this info is only for my printer?

 

I'm really sorry if my questions sound unclear or totally ignorant

 

Jen

[ronaldo_r]

Very common misunderstanding. Pls read this:

</br>

<a href="http://www.bobatkins.com/photography/digital/digital_image_resizing.html">www.bobatkins.com/photography/digital/digital_image_resizing.html</p>

</p>

[browncam]

The only stupid question is the one you don't ask.

[cosmic_c]

Jen - the quick answer to your question is, make sure the box labeled resample image is NOT checked when you change from 72 to 300dpi in Image size

 

You only check that box to when you want to actually reduce/increase the image dimensions such as when making a small web copy of the image.

[cosmic_c]

Re your last 2 questions

 

Levels and contrast should not affect the file size or rather the image size. (Obviously if you use layers for curves and levels and save the layered file it will be larger, but the image will be the same original size as can be seen by flattening the file)

 

Photoshop Preferences for New file are for when you create a New File ie file/new - in your instance your opening an existing file so the default will not apply. The screen resolution relates to when you use

view/print size command

[ronaldo_r]

"...resample image is NOT checked when you change from 72 to 300dpi in Image size..."

 

Actually, you can leave the PPI setting as it is. Doesn't affect anything under nrmal circumstances (i.e printing in a lab). Only concern yourself with the image size in pixels. Nothing else matters.

[paul_sokal___dallas__tx]

Did you save it as a JPEG?

[jennifer_arneson]

thanks guys

 

and Paul- yes, copy is in JPEG

[ronald_moravec1]

Never work on the original image. Open and save to PSD. Do the work and save. Now change name to xxxpsd 8x10 and resize. There will now be three files.

 

You can not keep changing a JPEG without losses and if yo make an error, you can not go back.

[paul_sokal___dallas__tx]

Jennifer, when you save as a JPEG you reapply the compression algorithm making a smaller file and reducing the quality of the image. If you save a JPEG file six or so times your reduced to a small pile of artifacts. I would never save a file as a jpeg except when I'm done processing it and it's ready for export, either to a printer, CD, or the web.