Just for Beginners, post your questions, ask for help, get opinions...
8 posts Page 1 of 1
I am having a heck of a time in CS3.
I resize an image for the web.
Image, resize, change my resolution to 72, then set my pixel size.
Save the image.
Go back and open the image and the resolution says 240. :doh:

So if I try to change to 72 again, my image size is too small.
I can't get anything to stick to 72 resolution.

HELP!!!!
~kimi~
Gone Crazy... Back Soon...


Gallery ~ a la kimi

My Blog

kimboustany.com
I checked a picture I just resized for the web in CS3 for the latest LR/ACR challenge, and when I opened it again it also shows as 240 ppi in the CS3 workspace.

Now, where I'm getting confused in your post, you say when you are doing a save for web operation, you are setting your resolution to 72 ppi. I'm not seeing where you can do that in the save for web window. When you do Image -> Resize in save for web, and set the width and height, you are not setting resolution but how many pixels wide and high your image will be.

My understanding of the save for web is that it provides a convenient method for setting a picture size (based on pixel count, not pixels per inch) and it also makes the conversion to the sRGB color space, which is used for web/monitor display, along with resampling the image to meet the size you specify. For instance, when I upload a picture for insertion into a post, I usually set the longest side to 450 - 475 pixels to minimize scrolling and keep the size of the file manageable. An image that starts out at 4278 pixels wde by 2848 pixels high and is a 5.2 Mb file, when resized to 475 pixels wide by 317 pixels high in save for web ends up turning into an 87 kb file. A significant difference, and a lot of resampling is being done on the image as a lot of pixels are being thrown away.

I think the 240 you are seeing in the bottom left corner of the CS3 workspace is the native resolution (ppi) CS3 displays at. You should also see your resaved picture is a lot smaller than what it started out at even though CS3 says its at 240 ppi. You can of course adjust that resolution via Image -> Image size, and if you do and resample and go to 72 ppi, that image is going to shrink quite a bit on your display. This is probably what you are seeing and are concerned about. Take that same image without resizing in the workspace and start the save for web process again, and you will see on the image size tab that it is still at the pixel dimensions you set the first time you saved it.

To illustrate my point, do this exercise on the CS3 workspace and reset the PPI of a photo and uncheck the resample box. The document size will change as reported in the resizing window, but you will not see the image change size on your display, and CS3 will report that image as being whatever PPI you chose to set it at. Print at that size, and your printer should print it at whatever document size the resizing dialogue said the picture would be. A lower PPI will give you a larger physical print, a higher PPI will give you a smaller (but higher quality) physical print. Resizing this way does not add or subtract pixels from your picture. It will either spread them out more (lower PPI) when you print, or squeeze them down (higher PPI) into a smaller physical dimension when you print. You will also see that the pixel dimension section in the resize window now sets itself so you can no longer change that dimension. The pixel width and height in this scenario doesn't change, but the size of the pixels (when printing) do.

Now, resize and check the resample box. You will now see the image size on your display change accordingly, but the resize window will not report a change in document size in inches, however, you will see the pixel dimensions change. Up the resolution and the pixel dimension will increase. Lower it, and the pixel dimension reduces. Document size in inches will stay the same either way. The reason your image resizes on your monitor at this point is because you are pretty much stuck at whatever your monitor resolution is (72 ppi for CRT and around 96 ppi for LCDs). The image resizes accordingly, and you are also adding or subtracting pixels in your picture when resizing with the resample box checked. This is also why picture quality is affected during resampling. CS3 is taking an "educated guess" on how to handle the pixels in the picture.

I hope this makes some sort of sense. :shock:
GeneVH

My SmugMug
My PrestoPhoto
Now on Flickr

CS5/LR4/Nikon D300 & D70s/Win7
Bottom line: when saving for Web/screen, ppi means nothing. Only thing that matters is pixel dimensions, which is what Save for Web uses. If you have an image that you resize to 1024 pixels by 768 pixels, it will fill a monitor screen (LCD or CRT) that's set to a resolution of 1024 by 768. If you display the same photo on a monitor that's set to 1680 by 1050 or 1440 by 900, the image will only fill a portion of the screen. If you want the image to fill one quarter of a screen that's set to 1024 by 768, the photo should be sized in Save for Web to 512 by 384 pixels.

All the stuff about 72 ppi and 96 ppi just serves to confuse, I'm afraid. Every monitor will display at several choices of pixel dimensions - and therefore will have a different ppi at each setting. For instance, I'm looking at a monitor that is set for 1440 by 900; that means that photos displayed here will have a ppi (pixels per inch of monitor) of 90 - not 72, not 96, not anything else.

Again, you should really forget/ignore/block out discussions of ppi when it comes to monitors. ppi DOES matter when it comes to printing, but not on the screen.

Can you tell I'm passionate about this topic?? :o Sorry for the strident tone.... For further reading on the subject, please go here:

http://www.scantips.com/no72dpi.html
Chuck
LR2/CS3/PSE6/Canon 450D, G10/Panasonic LX3
Gene... I didn't get a chance to go through and read everything you wrote. I'm moving fast.
Taking DD to airport.

I am saving for the web but not using the save for web feature.
I am just going into resize.

I found that if I opened the same image that said 240 in Elements it says 72.
So I just went in and saved everything in there.
I still don't get it and maybe you post explained.

will read it over throughly when I get back. Thanks!!
~kimi~
Gone Crazy... Back Soon...


Gallery ~ a la kimi

My Blog

kimboustany.com
Kimi,

Read Chucks post carefully.

I will wager that if you look at the ppi and document size in inches in both CS3 and PSE4/5/6/whatever you will find that when you multiply the pixels by the stated number of inches that you come up with the same number.

They are both the same thing, just a different representation.
John
yeah... so I don't have to care!! :woohoo:

I understood that when saving from 300 (camera image) to 72 (for web viewing) it was throwing away pixels?
I can see my images getting smaller when I choose 72 and my pixel dimensions I want for the web. I am saving images for my site at 750x460. So now Chuck's post explains everything perfectly for me. :biggrin:

In reality it does not matter if it says 240 when I go back and look at it... it is still fine?
~kimi~
Gone Crazy... Back Soon...


Gallery ~ a la kimi

My Blog

kimboustany.com
Yeah, Kimi. I never did understand why anyone would want to mess with the resolution for a web image. Too much trouble, and too much risk of screwing up a perfectly wonderful document by mistakenly saving a resized image.'

I think some bum information is being propagated on some other sites. :D
Sunny
My Galleries
Sunny's 12 OF 12
Canon 40D; EF 100mm f/2.8 macro USM; EF 50mm f/1.4 USM; Tamron 17-50 f/2.8; EF-S 55-250mm IS.
Believe in your heart that something wonderful is about to happen.
Well,

The truth is in the math. Check it out and let us know! :puter:
John
8 posts Page 1 of 1

Who is online

Users browsing this forum: No registered users and 3 guests

cron