I'm having a terrible time adjusting image size in Photoshop CS3. I've read Weinmann/Lourekas "Photoshop CS3" and Kelby's book of same title, and neither seem to give what I'm looking for.

Sites I upload pics to have max kb file sizes, say 600kb. So let's try one. I open a 1.6mb JPEG from Bridge to PS, click "Image/Image size", and get pop-up for image size change. According to the W/L primer, I click "Constrain Proportions" and "Resample Image/Bicubic Sharper (best for reduction)", leaving "Scale Styles" unclicked (Kelby kind of silent on the matter, but maybe I'm just not looking right). W/L then says to change "Resolution" from 240 pixels/inch, which is default print res, to 72 pixels/inch, which they explain is what's right for computer screens because they're low res. Which brings me to first question, are all computer screens low res, and if not, should I set to some higher res for viewing on possibly higher res computer screens, and what's wrong with using higher res anyway (I expect the latter has to do with poor gradation and distortion from cramming high pixels/inch onto low res screens, but just guessing)?

I then move on to the "Pixel Dimensions" or "Document Size" boxes on the pop-up, and see how changing either adjusts image size, but question becomes how in the world do I relate either of those selections to resulting file kb size, which is what I'm adjusting for (in this sample case , just under 600kb)? That's where go into trial-and-error land, with a 1.6mb JPEG reduced to 800x600 pixel dimension (I'm shooting Olympus 4/3) sometimes giving me the targeted just-under 600kb files, but at other times giving me anywhere from 400-750kb files. Of course, not all my JPEGs are 1.6mb, range is roughly from 1.0-2.4mb, so this is another variable I'm guessing further stirs the soup. Would be awfully nice to find a way to enter kb size file desired, with PS adjusting image size to that. PS does show pixel dimension image size at top of pop-up, both original and what it reduces to, and I tried using that as indicator of what saved kb size would be, but results seemed all over the lot. I'm missing something here that's pretty basic, and probably pretty obvious, but expect I'm not the first.

Another question under this same umbrella involves the pop-up I get after clicking "Save as ...", which asks for selection up to grade 12, which PS calls "Maximum", and is what I usually opt for just because who doesn't want maximum. This pop-up also allows "baseline" selection, a term I see in my primers only with reference to text presentation. I can't find anything in either book on this pop-up, a total blank.

Sorry to be posting all this. I've been able to take myself pretty far into PS (well, just the outside layer, but that allows a lot!). but am baffoned by this matter of image size. Thanks in advance for taking the time to read and help out.

Originally Posted by jimphotog Sites I upload pics to have max kb file sizes, say 600kb. So let's try one. I open a 1.6mb JPEG from Bridge to PS, click "Image/Image size", and get pop-up for image size change. According to the W/L primer, I click "Constrain Proportions" and "Resample Image/Bicubic Sharper (best for reduction)", leaving "Scale Styles" unclicked (Kelby kind of silent on the matter, but maybe I'm just not looking right). W/L then says to change "Resolution" from 240 pixels/inch, which is default print res, to 72 pixels/inch, which they explain is what's right for computer screens because they're low res. Which brings me to first question, are all computer screens low res, and if not, should I set to some higher res for viewing on possibly higher res computer screens, and what's wrong with using higher res anyway (I expect the latter has to do with poor gradation and distortion from cramming high pixels/inch onto low res screens, but just guessing)?

Computer screens hover around 100 dpi these days, but it matters about >< this much for posting on the web, browsers like to display pictures based on actual pixel dimentions so this setting changes nothing. It's just a bit of data to tell size aware software and more importantly printers the scale from pixels to inches or centimeters or whatever.

Distorsions pop up if you resize with 'Nearest neighbour', the bicubics are fine.

Originally Posted by jimphotog I then move on to the "Pixel Dimensions" or "Document Size" boxes on the pop-up, and see how changing either adjusts image size, but question becomes how in the world do I relate either of those selections to resulting file kb size, which is what I'm adjusting for (in this sample case , just under 600kb)? That's where go into trial-and-error land, with a 1.6mb JPEG reduced to 800x600 pixel dimension (I'm shooting Olympus 4/3) sometimes giving me the targeted just-under 600kb files, but at other times giving me anywhere from 400-750kb files. Of course, not all my JPEGs are 1.6mb, range is roughly from 1.0-2.4mb, so this is another variable I'm guessing further stirs the soup.

A jpeg's size depends on what the image looks like. Lots of contrasts like branches against sky give big files. Image noise will also increase file sizes.

Try selecting a size which puts you in the ball park on file size, it doesn't have to match at this point. The trick comes next...

Originally Posted by jimphotog Another question under this same umbrella involves the pop-up I get after clicking "Save as ...", which asks for selection up to grade 12, which PS calls "Maximum", and is what I usually opt for just because who doesn't want maximum. This pop-up also allows "baseline" selection, a term I see in my primers only with reference to text presentation. I can't find anything in either book on this pop-up, a total blank.

That number is the amount of compression put into the final image file. This is a major tool file size wise. You can try the 'Save for web' tool, which will give you a nice preview of how the compression affects the image with the respective file sizes. I tend to use 12 for prints and 7-9 for web. This tool will also let you resize, give it a shot.

'Baseline' and 'progressive' are two ways of building a jpg. The first is more common, the usual way of doing it and works well. Progressive gives you a very rough image first which then sharpens up over several passes as the image loads, it's almost a thing of the past now.

Originally Posted by jimphotog Sorry to be posting all this. I've been able to take myself pretty far into PS (well, just the outside layer, but that allows a lot!). but am baffoned by this matter of image size. Thanks in advance for taking the time to read and help out.

Here's something you could try. Put the books down and just play with it every now and then. I'm not saying you should abandon them all together, but 'I wonder what this doodad does' is actually a good way to learn as well

Originally Posted by pyry Computer screens hover around 100 dpi these days, but it matters about >< this much for posting on the web, browsers like to display pictures based on actual pixel dimentions so this setting changes nothing. It's just a bit of data to tell size aware software and more importantly printers the scale from pixels to inches or centimeters or whatever. Distorsions pop up if you resize with 'Nearest neighbour', the bicubics are fine. A jpeg's size depends on what the image looks like. Lots of contrasts like branches against sky give big files. Image noise will also increase file sizes. Try selecting a size which puts you in the ball park on file size, it doesn't have to match at this point. The trick comes next... That number is the amount of compression put into the final image file. This is a major tool file size wise. You can try the 'Save for web' tool, which will give you a nice preview of how the compression affects the image with the respective file sizes. I tend to use 12 for prints and 7-9 for web. This tool will also let you resize, give it a shot. 'Baseline' and 'progressive' are two ways of building a jpg. The first is more common, the usual way of doing it and works well. Progressive gives you a very rough image first which then sharpens up over several passes as the image loads, it's almost a thing of the past now. Here's something you could try. Put the books down and just play with it every now and then. I'm not saying you should abandon them all together, but 'I wonder what this doodad does' is actually a good way to learn as well

What's do you mean by "resize with nearest neighbor" with reference to distortions popping up?

Re resolution, I think you're saying that for web output just leave default as is, at 240, one less thing to think about. Correct?

Re dimensions, you hit the nail on the head when you said get it close to size (I used 8'x10"), then click "Save for web and devices ...", and watch the magic!!! When I tried "Save for web ..." earlier on my own, I didn't reduce size first, so kept getting pop-up saying file was too large. On the "Save for web ..." pop-up, I played with the 2-up and 4-up, but "Optimize" looked best, so selected that and "Maximum" ("Quality" box changed from 80 to 100), and got a 585k file (I'm guessing that's just happenstance that's so close to the 600k I earlier was shooting for). Home free!!! Then I clicked "Save", though, and the 585k became 181k in my pic folder. So another dumb question, does the 181k decompress back up to 585k when someone opens it after I upload it, or am I still not understanding? If that's not what happens, what does the 585k mean, why do I care if 181k is all I'm getting?

Regarding the few pics already re-sized to just below 600k in my pic folder (correlates to the 181k mentioned above), will they look any better (sharper, better gradation) when down loaded and opened than the optimized 181k file, or just require scrolling to see full dimension of pic, or what?

Two final questions: how do I insert my responses between paragraphs of a thread posting the way you do, and where in the world do you find time to help the rest of us out? RE the latter, I owe you one.

Thanks for all the other do-dads, and your advice of course to just click around is well taken. I've done a lot of that, truly have, but was hitting a brick wall on re-sizing cause I didn't make that initial ballpark reduction first. So obvious when one knows the flow.

If you can take another moment to answer remaining questions, I'd sure appreciate it. Thanks again.

I haven't read those books but what I do for specific sizes is to do to image size and changes dpi to get to the nearest physical size I want with my 6mp files i start out at 400dpi constrain proportions....this bring my files some between 8 x 10 and 4 x 6 inches.....I play until I have what I think I really want....then under file I DO NOT SAVE AS but rather SAVE FOR THE WEB.....then I play with the pop up until I have it where I want it and then clik the save button......this is only done for SAVING FOR THE WEB.....this also strip out the exif data and if I have to get my files real small I do not car about that any way.....this has been the way I have done it since PS4 and it has always gotten acceptable results for me.

Originally Posted by jimphotog leaving "Scale Styles" unclicked (Kelby kind of silent on the matter, but maybe I'm just not looking right).

Don't worry about this part. Scale Styles is about scaling Layer Styles, which give you drop shadows, embossing, etc. in other words graphic design effects for web page buttons and such. They are not used in photo editing.

Originally Posted by Art Scott I haven't read those books but what I do for specific sizes is to do to image size and changes dpi to get to the nearest physical size I want with my 6mp files i start out at 400dpi constrain proportions....this bring my files some between 8 x 10 and 4 x 6 inches.....I play until I have what I think I really want....then under file I DO NOT SAVE AS but rather SAVE FOR THE WEB.....then I play with the pop up until I have it where I want it and then clik the save button......this is only done for SAVING FOR THE WEB.....this also strip out the exif data and if I have to get my files real small I do not car about that any way.....this has been the way I have done it since PS4 and it has always gotten acceptable results for me.

Thanks, Art. Combined with what other I got here, I'm on my way. The one thing I was screwing up was not downsizing before clicking "save for web", so the few times I tried it I got pop-up "file to large". Now tht I downsize first, works just fine.

Originally Posted by colourbox Don't worry about this part. Scale Styles is about scaling Layer Styles, which give you drop shadows, embossing, etc. in other words graphic design effects for web page buttons and such. They are not used in photo editing.

Thanks for input. For the life of me, I couldn't figure put what that was.

Originally Posted by jimphotog What's do you mean by "resize with nearest neighbor" with reference to distortions popping up?

Nearest neighbour is one the resampling methods offered by PS. It just strips pixels off the image without thinking about it too much. Nice and fast, but leads to images which look like they don't fit together any more. Try it and you'll see what I mean

Originally Posted by jimphotog Re resolution, I think you're saying that for web output just leave default as is, at 240, one less thing to think about. Correct?

Yes.

Originally Posted by jimphotog Re dimensions, you hit the nail on the head when you said get it close to size (I used 8'x10"), then click "Save for web and devices ...", and watch the magic!!! When I tried "Save for web ..." earlier on my own, I didn't reduce size first, so kept getting pop-up saying file was too large. On the "Save for web ..." pop-up, I played with the 2-up and 4-up, but "Optimize" looked best, so selected that and "Maximum" ("Quality" box changed from 80 to 100), and got a 585k file (I'm guessing that's just happenstance that's so close to the 600k I earlier was shooting for). Home free!!! Then I clicked "Save", though, and the 585k became 181k in my pic folder. So another dumb question, does the 181k decompress back up to 585k when someone opens it after I upload it, or am I still not understanding? If that's not what happens, what does the 585k mean, why do I care if 181k is all I'm getting?

I think what's going on here is that the image size pallette doesn't know that you're going to use compression and hence always talks about uncompressed file sizes. The 'Save for web' tool should give you an estimate based on the compression selected.

Originally Posted by jimphotog Two final questions: how do I insert my responses between paragraphs of a thread posting the way you do, and where in the world do you find time to help the rest of us out? RE the latter, I owe you one.

Look for a [quote*= someone] and a [/quote*] tag when you reply. Just copy and paste those around to split comments. (without the asterisks, I put those in to show the tags)

The time comes from the same (rather big ) pool I draw from to browse the forum. And lending a hand is one of the reasons this place exists and works so well

Originally Posted by pyry Nearest neighbour is one the resampling methods offered by PS. It just strips pixels off the image without thinking about it too much. Nice and fast, but leads to images which look like they don't fit together any more. Try it and you'll see what I mean Yes. I think what's going on here is that the image size pallette doesn't know that you're going to use compression and hence always talks about uncompressed file sizes. The 'Save for web' tool should give you an estimate based on the compression selected.

Sounds right. Tried it, and sure enough, properties on opened pic indicate 585k/

Originally Posted by pyry Look for a [quote*= someone] and a [/quote*] tag when you reply. Just copy and paste those around to split comments. (without the asterisks, I put those in to show the tags)

OK, trying tags around paras responded to. Is it working?

Huge help, and thank you. O pick up a bit more talent, I'll do some responding myself. You're right, this is a friendly place.

Originally Posted by jimphotog OK, trying tags around paras responded to. Is it working?

I think you missed a closing quote tag in there, because I got a beginning tag citing meself for this reply. But you're on the right track

A few brief comments

Images destined for the Web are best dimensioned in pixels - not inches, not dots, but total pixels on each edge in the Image > Size command.

Images destined for a printer are best dimensioned in inches with pixels per inch set to an appropriate value for the destination printer - typically somewhere between 240 pixels per inch, and 360 pixels per inch. For very large images, viewed no closer than 5 feet or so, you might use 180 pixels per inch.


DPI, or dots per inch, refers to the output pattern of an inkjet print head, and has nothing to do with image resizing. Art talked about dpi, but I believe he really was talking about ppi.

For every image pixel that is sent to an inkjet printer, the printer may output anywhere from 2 or 3 to as many as 10-20 dots per inch, and the user has no control over how many dots per pixel are output. ( For example, you can specify in the printer driver whether to print at 720dpi, or 1440dpi, or 2880dpi in the Epson driver, but this does not let you specify the number of dots per pixel - that is proprietary and controlled by the printer driver software.

Keeping ppi and dpi straight is helpful for clarity of discussion.

Originally Posted by pathfinder A few brief comments Images destined for the Web are best dimensioned in pixels - not inches, not dots, but total pixels on each edge in the Image > Size command. Images destined for a printer are best dimensioned in inches with pixels per inch set to an appropriate value for the destination printer - typically somewhere between 240 pixels per inch, and 360 pixels per inch. For very large images, viewed no closer than 5 feet or so, you might use 180 pixels per inch. DPI, or dots per inch, refers to the output pattern of an inkjet print head, and has nothing to do with image resizing. Art talked about dpi, but I believe he really was talking about ppi. For every image pixel that is sent to an inkjet printer, the printer may output anywhere from 2 or 3 to as many as 10-20 dots per inch, and the user has no control over how many dots per pixel are output. ( For example, you can specify in the printer driver whether to print at 720dpi, or 1440dpi, or 2880dpi in the Epson driver, but this does not let you specify the number of dots per pixel - that is proprietary and controlled by the printer driver software. Keeping ppi and dpi straight is helpful for clarity of discussion.

Very good, and thanks. But not sure it solves what I'm bumping against. My goal is in terms of kb, to downsize to just below 600 kb, so if using "pixel size" for resmapling, question becomes how to mentally convert pixels into equivalent kb. To get the immediate job done, I used "dimension size", setting edges at 8 x10 inches (at times a bit more or less, apparently depending on amount of contrast and detail in pic) combined with 100 resolution (suggested as highest screen res I'd probably run into). By following with "Save for web ..." and using the resulting pop-up's flexibility for kb size fine tuning, I got what I wanted with very little adjustment (most ended up between 95-100 on quality scale). So question is, if I should be using "pixel size" to downsize for web, how do I relate to resulting kb size? Or is it of no real matter, so long as I get to my max 600 kb in the end? Or am I still totally in left field on this thing?

Originally Posted by pathfinder A few brief comments Images destined for the Web are best dimensioned in pixels - not inches, not dots, but total pixels on each edge in the Image > Size command. Images destined for a printer are best dimensioned in inches with pixels per inch set to an appropriate value for the destination printer - typically somewhere between 240 pixels per inch, and 360 pixels per inch. For very large images, viewed no closer than 5 feet or so, you might use 180 pixels per inch. DPI, or dots per inch, refers to the output pattern of an inkjet print head, and has nothing to do with image resizing. Art talked about dpi, but I believe he really was talking about ppi. For every image pixel that is sent to an inkjet printer, the printer may output anywhere from 2 or 3 to as many as 10-20 dots per inch, and the user has no control over how many dots per pixel are output. ( For example, you can specify in the printer driver whether to print at 720dpi, or 1440dpi, or 2880dpi in the Epson driver, but this does not let you specify the number of dots per pixel - that is proprietary and controlled by the printer driver software. Keeping ppi and dpi straight is helpful for clarity of discussion.

Very good, and thanks. But not sure it solves what I'm bumping against. My goal is in terms of kb, to downsize to just below 600 kb, so if using "pixel size" for resmapling, question becomes how to mentally convert pixels into equivalent kb. To get the immediate job done, I used "dimension size", setting edges at 8 x10 inches (at times a bit more or less depending on amount of contrast and detail in pic) combined with 100 resolution (suggested as highest screen res I'd probably run into). By following with "Save for web ..." and using the resulting pop-up's flexibility for kb size fine tuning, I got what I wanted with very little adjustment (most ended up between 95-100 on quality scale). So question is, if I should be using "pixel size" to downsize for web, how do I relate edge pixels to kb size, other than the time-consuming trial and error I originally was trying? Or is it of no real matter, so long as I get just below my max 600 kb in the end? Or am I still totally in left field on this thing?

Thanks again for taking the time.