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Hurricane Katrina damaged photos

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  #11  
Old 01-17-2008, 09:52 PM
Craig Walters's Avatar
Craig Walters Craig Walters is offline
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Re: Hurricane Katrina damaged photos

hi jlachin,

ah, the old raise resolution but lower image size. this is a pretty common mistake. in actual fact, you've still got the same size here, effectively. i'll try to explain.

resolution is, when talking about digital images, the number of pixels (picture elements) or dots per inch (or the metric equivalent). that's all resolution is. but, IMAGE SIZE is the overall number of pixels width by length. but, there is another factor that gets entered in sometimes and that's the one that confuses things, PRINT SIZE, you know, like 4 x 6 or 5 x 7 or 8 x 10. the trouble comes in that you can print an 8 x 10 at different resolutions regardless of IMAGE SIZE. you seem to be going by PRINT SIZE when you're saving your image for posting. we dont want that. we want how many pixels by how many pixels. that's ALL that really matters.

it's a little screwy, i know. the easiest way to save images for posting on the internet is by pixels, not format or print size. dont save in 4x6 or 8x10 or any of those. save in pixels and the bigger the better.

when you're printing an image, resolution does matter. if you have a 4x6 print at 300 ppi (pixels per inch) it's much better than a 4x6 at 100 ppi. basically, you're forcing all that higher resolution down into that little 4x6 image, but when on the monitor or the internet, that 4x6 means very little and is very misleading. the reason for this is that photoshop and other editors just take that resolution and make a larger image size. so, if you have a 4x6 at 300 ppi, the image will expand to 4x300 by 6x300 or 1200 x 1800 pixels. but, if that same image is 4x6 at 100 ppi, it will be 4x100 by 6x100 or 400 x 600. it's still a 4x6 image, essentially... for print. but the actual size of the image increases on your monitor.

with me so far? so, in print, resolution is a multiplier. it squishes more dots into the print the higher the resolution. but, a monitor cant squish all those dots down so it just enlarges the image size to display the whole thing.

so, the solution here, on the internet, when someone asks you for a 'higher resolution' is, dont save or even work with print sizes like 4x6 and 5x7 and so on. work in pixels! they are asking for more pixels in the image which is going to result in a larger image (and file size). that make sense?

it is a bit confusing, but that's how the system works.

basically, what you did was swap resolution for print size and that just results in the same image size on a monitor. you simply reversed them and still wound up with the same image size. here's a simple equation: resolution times print size equals image size. what we want is a larger IMAGE SIZE. we tend to say we want a larger resolution but that's only really half of it. we want a higher resolution AND a higher print size which gives a larger image size.

oh, and scanning at 600 ppi is fine. that shld be enough. if you can actually scan at higher, why, great, but 600 shld be ok. what we really want is that bigger image size plus that 600 ppi scan. you dont have to convert it to 1200 digitally.

i think the photoshop guys recommend using 'save for web' when saving. that seems to be what i hear most from the ps folks. try that. and, get used to thinking in pixels.

and please, dont worry; it's a common mistake and you eventually get used to thinking in pixels
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  #12  
Old 01-18-2008, 08:14 AM
jlachin jlachin is offline
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Re: Hurricane Katrina damaged photos

Ok, wow thank you for that. I've really been trying to make sense of this for a while and I'm still trying to make sense of it! Just when I start making sense of it, I read something that contradicts what I previously thought I understood! Maybe it will help if I try to explain to you what I believe I understand and what I had been doing. I thought that by taking my scans, opening them up, and increasing the ppi from 600 to 1200, that this would increase the resolution of my image. But what I've noticed and understood is that it only increases the size of the image when I increase the ppi and this makes sense because I actually see the size increase on my screen and therefore the ppi is essentially the same as it was before. So I guess what I'm still confused is how do I REALLY increase the pixels in Photoshop CS3 without changing the image size? Thanks so much for your patience!!!! This is definitely something that I would love to have a good understanding about and I really do appreciate your explanations!
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  #13  
Old 01-18-2008, 09:37 AM
videosean videosean is offline
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Re: Hurricane Katrina damaged photos

Your scans look fine to me... assuming they've been made smaller to allow them to be uploaded to photobucket they look very clean and clear otherwise.
More resolution = more pixels. Higher ppi setting = more pixels.
Let's say the print you have is 3x5 inches. Scanned at 600 ppi that makes an 1800x3000 pixel image (multiply the height and width by your ppi to get the pixel dimensions) and scanned at 1200 ppi it would be 3600x6000 pixels.
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But what I've noticed and understood is that it only increases the size of the image when I increase the ppi and this makes sense because I actually see the size increase on my screen and therefore the ppi is essentially the same as it was before.
ppi has little or nothing to do with what's on your screen. You can measure a print because it is a fixed medium of sorts... whereas a monitor is not fixed. The ppi of any monitor will depend on what the desktop resolution is set to. Basically, when it comes to digital images on a display device, pixels is what matters not PixelsPerInch. I'm completely confused as to why you think ppi is the same in two different images that have different pixel counts... but hopefully we can help
Quote:
So I guess what I'm still confused is how do I REALLY increase the pixels in Photoshop CS3 without changing the image size?
You don't basically. You increase the pixels in this case by scanning at a higher ppi setting and that setting is technically in your scanner's software interface, not photoshop. Unless you mean resampling in which your software will make up new pixels... I don't recommend doing that but in photoshop go to Image->ImageSize and make sure there's a check in the box next to 'Resample Image'. More on resampling: http://jura.wi.mit.edu/bio/graphics/...htm#resampling

You scanned your 3x5 at 600 ppi and it's 1800x3000 pixels. When you print that file at a size of 8x10 it will have 225 ppi. 1800 / 8 = 225. Same digital image, same pixel count, different print size... that's where ppi matters... IMO or my way of thinking at least.
A 3x5 scanned at 1200 ppi would be 450 ppi at an 8x10 print size.

If I've completely confused you I apologize and offer a link
http://www.scantips.com/basics01.html

Last edited by videosean; 01-18-2008 at 09:48 AM.
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  #14  
Old 01-19-2008, 11:57 PM
Craig Walters's Avatar
Craig Walters Craig Walters is offline
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Re: Hurricane Katrina damaged photos

Quote:
Ok, wow thank you for that. I've really been trying to make sense of this for a while and I'm still trying to make sense of it! Just when I start making sense of it, I read something that contradicts what I previously thought I understood! Maybe it will help if I try to explain to you what I believe I understand and what I had been doing. I thought that by taking my scans, opening them up, and increasing the ppi from 600 to 1200, that this would increase the resolution of my image.
yes, it will increase the resolution. and yes, i do understand about contradictions. so, let's have some concrete evidence here that you can actually look at and compare and see what's going on yourself. let's take your attachment in post #8 here and your other attachment in post #10. the first is called 'largegroup.jpg' and the second is 'largegroup1.jpg'. open them both up here from this thread in your browser. make sure they are open all the way so that you see them in the larger size. now, right click on each of them and pick 'properties' from the little menu that opens up. notice in the window where it says 'dimensions'. you'll notice in BOTH images that it says '1024x710 pixels'. ah. they are both the same! and they show up on the monitor the same! that's because they are the same. the key here is that we're looking at the 'pixel' size, NOT the print size.

now, if you were to take both of those images into photoshop, paint shop pro or any other decent editor, you could also look at an 'info' window of that image. you would still see the pixel dimension is the same on both, but lo and behold, the resolution is different! huh? how can that be? they are both the same size but they have different resolutions, so they shld be different sizes, shldnt they? yeah, that's the one that gets everyone new to this. they are the same size even though they have different resolutions. what happens is that unless you command your editor to do otherwise, it will lower the inches size while it raises the resolution which keeps it exactly the same pixel size!

here it is in stone: PIXEL SIZE EQUALS RESOLUTION TIMES INCHES!

thus, a 600 resolution at 4 inches, is the same as a 1200 resolution at 2 inches IN PIXEL SIZE. 600 x 4 = 2400 pixels; 1200 x 2 = 2400 pixels. they are the same beast in pixel size.

and if you're working in metric sizes, it's still the same. just substitute your metric values in where i've said inches.

what we want you to increase is the pixel size. that means keeping either inches the same and raising resolution or keeping resolution the same and raising inches. that will get you a larger pixel size. but remember, you have to command your editor to do it this way, otherwise it will raise resolution but lower inches giving you the same pixel size you had when you started.

and that's why your pixel size hasnt changed in your attachments
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  #15  
Old 01-23-2008, 01:36 AM
shaunx shaunx is offline
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Re: Hurricane Katrina damaged photos

That was sad... it was a curse day to be remembered..Condolences for all who passed away..
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