image resampling in photoshop

[mahmoudf93159457]

when the resample option is checked on "in image size command" and i change "increase or decrease" the resolution why  the document size for printing doesn't change and when i change the image dimensions on screen the resolution is fixed and document size for printing change ?

[Chuck Uebele]

That's what resample does. It changes the physical size of your image (pixel dimension). So with resample, the other fields like resolution doesn't change if you change image dimension and visa-versa. If you don't resample the pixel size doesn't change, so if you change the resolution, the image size in inches, cm, or whatever has to change to keep the pixel dimension the same.

[JJMack]

Because when you resample you create a new image with fewer or more pixels.  To print size will  be what is set. the Image size and will print the same sizeas the original image if you just change the Print DPI with Resample check.  A different number of pixels will be in the new images the print will be the same size printed with the Pixels size set in the Print DPI resolution.  The Number of Pixels are different and the Print Pixel size is different then the original image.  Its a different image with a degraded image quality.

[mahmoudf93159457]

thanks for your explanation

but when i change the image dimensions on the screen "width and height" the resolution doesn't change and the print size change ? this is confusing me

[JJMack]

That is correct the image print size will  change because the number of pixels has been  change and they will be printed with the same size pixels as the originals image.  When you resample an you create a new image with a different anount of pixels.

When you do not resample all that changes is the print size the image pixels are  not change they are printed with  different DPI pixel size.

Print DPI Resolution is the size a image will be print with.  It is a meaningless when it come to displays Displey can not change the pixel size the display.  Printers can change the size they print pixel down to their max resolution

[Chuck Uebele · Accepted solution]

Width and height is the printing dimension. So, as I mentioned before. Resampling will change the pixel dimension and not change the other (resolution or width and height) depending on which you change. If you uncheck resample everything except pixel dimension  will change. Pixel dimension is the true size of your image. The other ones are just relative numbers and really have no impact on a file's actual size.

[mahmoudf93159457]

the last sentence made everything clear thanks

[ThaiMcTours]

Thanks very much! I understand pixels/size relationship (I tend to work in pixels now anyway, too lazy to alter the settings for every single site/app?!), however the more pixels/worse resolution still confuses me... Will cut to the chase, am putting a new website for ourselves (touring, so pictures really important) together and what I'd really like to do is take a bunch of old photos, and really sharpening them up with some optimal settings as may be applied using  Fotor / AI Image enlarger (online only, daily limits) so am able to fly through a load ASAP?