All,

I'm trying to figure out how to "downsize" or "downsample" my images to 4mp for the purpose of either noise reduction or once I am approved at Shutterstock.

I have Photoshop Elements 6.0. (Full version)

I currently know to go to Image/Resize/Image Size which then brings up the dialog box of choices ... depending on whether "resample" is checked or not I can edit the Pixel Dimensions and the Document Size. The only place I see the mega pixels is in the pixel dimensions so I believe I have to have "resample" checked. Is this correct? If so to what width and height do I set this to to achieve a 4mp image for shutterstock.

Also there is a box where I can enter the Resolution which defaulted to 180 mp

Any help with how to do this in Photoshop Elements 6.0 would be a great help.


Mark

http://en.wikipedia.org/wiki/Pixel

Under "Standard display resolutions"

Mark, be careful not to confuse Megapixels with Megabytes.

Shutterstock lists their minimum size as 2400 x 1600 = 3.8mp so all you have to do is make the long side 2400 and make sure the short side is at least 1600, and you have it.

Hope that makes all the math easier? 

Nope, it's 4.0 MP. Says so right on their upload page.
Also, his camera gives 4:3 images, not 3:2 ones.

Oops = Sorry. I took that number 2400x1600 off someones guide to microstock site. But here's another answer to the question that gets asked about size requirements there. "The minimum size for new photographers is now 4.0MP."

Another source lists 4 megapixels as 2,272x1,704. 

Sensor res-4.0 megapixels Image dimensions-2464x1632 for Nikon

Third source = 4 megapixel image with dimensions of 2272x1704 again.

I like your calculations (Sharply) which will set the base minimum and keep us safely at 4 mp. 2460 x 1640 for a 3:2 camera.

I just submitted some photos at 2400, so now I can be ready for the rejection.

Thanks for clearing it up, and correcting my notes.

OK.  If I'm reading your post correctly, it looks like you may be confusing megapixels (mp) with megabytes (mb).  It looks like you have an 8 mp camera.  So if you multiply the camera's raw output height by width in pixels, the result should be somewhere around 8,000,000 (it won't be exactly that, but should be close).  As a TIF file, the file size  will be somewhere around 20-22 mb.  Note this is not the same as the image size.  That stays at 8 mp

The only thing you need to worry about is the height and width in pixels.  I think you already know how to do that, so won't repeat it.  When you come up with a 4 mp image, the TIF file will be much smaller than the original 20-22 mb, but most likely much larger than 4 mb.  And if you save that as a JPEG, it will be smaller yet.  But it will still be a 4 mp image.

Think of it like this.  megapixels (mp) is the physical size of your image.  Megabytes (mb) is the size of the space your image will take up on your hard drive (or elsewhere).  For SS, all they care about is the physical size of the image.  The file size (in megabytes) is not relevant.

Hope this helps.  If you already knew all this and I just misread your original question, I apologize.

w7lwi

Actually your explanation helps quite a bit. Hatman pointed out that I was starting to get confused about MP and MB above. From my trial and errors working on this over the weekend while consulting this post ... combined with your crystal clear explanation, it all makes sense.

I was confused by looking at the file size (mb) on my hard drive, rather than the image size in megapixels.

Here's a summary of what I have learned from everyone's help regarding "downsizing" an image. (Note: I use PS Elements 6.0 Full Version)

#1 JPG comes off the camera (my camera does not support raw) at the highest quality and image resolution possible

#2 Save as .tiff for post-processing
 
#3 in PS Elements 6.0. Goto Image/Resize/Image Size and Set Pixel Dimensions to Width and Heigth to 2312 x 1734 for 4:3 images or 2460 x 1640. Also Have Resample Image Box Checked and Bicubic Sharper set in the pull down menu as "bicubic" is set as the default

#4 End result is a  a 4.009 mp (2312 x 1734 = 4.009) photo that shows as only 2.8 MB file for storage purposes on my hard drive which was created from a 39.5 MB .tiff file.

I hope that this will help the next person who has "downsizing" questions in the future.

Thanks

Mark