Image Reductions without pixelation

[David]

Greetings, I'm trying to sort out the best way to reduce an image in GC without pixelation. I've read that in PShop, both "bicubic" and "bilinear" yield good results, but I don't see anything that appears to be the obvious equivalent of "bilinear" in GC. The starting image is a 600dpi JPG and very clear with no obvious artifacts. My usual method is to do any cropping and then resave as a TIF...then do resolution and size changes. I've not yet had satisfactory results, and my patience for trial and error is gone. I was hoping for some feedback from those that know more about the scaling algorithms in GC. I seem to recall that details about these were going to be added to the manual, but perhaps I've missed something. This is something that SHOULD be simple, but there are times when the solution is right under my nose and I just don't see it. Thanks in advance for any help and advice.

[Marino Pascal]

David, Maybe it would help if you posted original image and result (undesireable or not) Also you shouldn't mess with changing the dpi. DPI only made sense during the scanning days. Once the picture is in the computer there is no reason to change the dpi. All you should worry about is the width and height dimensions preferrably in pixels. All you need to know about dpi is this: you are looking at images on your screen at 75 dpi (72 to be exact) A good print, prints at 300 dpi Therefore whatever size looks good on your screen, needs to be 4 times larger (75x4=300) double width x double height to produce same quality print of equivalent dimensions. In other words if 1024x768 looks good on your screen, you'd need 2048x1536 for a print of the same quality and dimensions. Marino David wrote: > Greetings, > > I'm trying to sort out the best way to reduce an image in GC without pixelation. > > I've read that in PShop, both "bicubic" and "bilinear" yield good results, but I don't see anything that appears to be the obvious equivalent of "bilinear" in GC. > > The starting image is a 600dpi JPG and very clear with no obvious artifacts. My usual method is to do any cropping and then resave as a TIF...then do resolution and size changes. > > I've not yet had satisfactory results, and my patience for trial and error is gone. I was hoping for some feedback from those that know more about the scaling algorithms in GC. I seem to recall that details about these were going to be added to the manual, but perhaps I've missed something. > > This is something that SHOULD be simple, but there are times when the solution is right under my nose and I just don't see it. > > Thanks in advance for any help and advice. > > > > > ------------------------------------ > > Yahoo! Groups Links > > > >

[Carter Crain]

Re: [gcmac] Image Reductions without pixelation Why do you want to reduce the size? After trying to understand all the different possibilities, I settled on mainly reducing the jpeg quality to about 30%. Sometimes I reduced the size and/or the pixels per inch. My main use was to put pictures on a website. I do not think this the most sophisticated way to do it but it seemed to be practical for my purposes.   On 5/15/08 7:06 PM, "Marino Pascal" <weblists@locationscout.com> wrote:   David, Maybe it would help if you posted original image and result (undesireable or not) Also you shouldn't mess with changing the dpi. DPI only made sense during the scanning days. Once the picture is in the computer there is no reason to change the dpi. All you should worry about is the width and height dimensions preferrably in pixels. All you need to know about dpi is this: you are looking at images  on your screen at 75 dpi (72 to be exact) A good print, prints at 300 dpi Therefore whatever size looks good on your screen, needs to be 4 times larger (75x4=300) double width x double height to produce same quality print of equivalent dimensions. In other words if 1024x768 looks good on your screen, you'd need 2048x1536 for a print of the same quality and dimensions. Marino David wrote: > Greetings, > > I'm trying to sort out the best way to reduce an image in GC without pixelation. > > I've read that in PShop, both "bicubic" and "bilinear" yield good results, but I don't see anything that appears to be the obvious equivalent of "bilinear" in GC. > > The starting image is a 600dpi JPG and very clear with no obvious artifacts. My usual method is to do any cropping and then resave as a TIF...then do resolution and size changes. > > I've not yet had satisfactory results, and my patience for trial and error is gone. I was hoping for some feedback from those that know more about the scaling algorithms in GC. I seem to recall that details about these were going to be added to the manual, but perhaps I've missed something. > > This is something that SHOULD be simple, but there are times when the solution is right under my nose and I just don't see it. > > Thanks in advance for any help and advice. > > > > > ------------------------------------ > > Yahoo! Groups Links > > > >       

[Don Sample]

On 15-May-08, at 8:06 PM, Marino Pascal wrote: > David, > Maybe it would help if you posted original image and result > (undesireable or not) > Also you shouldn't mess with changing the dpi. > DPI only made sense during the scanning days. > Once the picture is in the computer there is no reason to change the > dpi. All you should worry about is the width and height dimensions > preferrably in pixels. > > All you need to know about dpi is this: > you are looking at images on your screen at 75 dpi (72 to be exact) It's very rare to find a 72 dpi screen these days. The one I'm using now is closer to 90, and most are higher than that.

[Gordon Alley]

Just calculated the DPI on my new iMac 24" screen: 1920px / 20.5in = 94dpi.For my MacBook, its 1280px/11.25in = 114dpi.-Gordon On Fri, May 16, 2008 at 10:39 AM, Don Sample <dsample@mac.com> wrote: On 15-May-08, at 8:06 PM, Marino Pascal wrote: > David, > Maybe it would help if you posted original image and result > (undesireable or not) > Also you shouldn't mess with changing the dpi. > DPI only made sense during the scanning days. > Once the picture is in the computer there is no reason to change the > dpi. All you should worry about is the width and height dimensions > preferrably in pixels. > > All you need to know about dpi is this: > you are looking at images  on your screen at 75 dpi (72 to be exact) It's very rare to find a 72 dpi screen these days.  The one I'm using now is closer to 90, and most are higher than that. -- Gordon B. Alleyhttp://www.gordonalley.com

[Marino Pascal]

Carter Crain wrote: > Why do you want to reduce the size? > > After trying to understand all the different possibilities, I settled on > mainly reducing the jpeg quality to about 30%. But that's terrible. That's why your pictures are pixelated. >Sometimes I reduced the > size and/or the pixels per inch. My main use was to put pictures on a > website. For the web I use 85% quality and 1024x768 pixels dimensions. My average image is about 150KB without the resource fork which gets lost during uploading. Marino > -- Marino Pascal 2525 Crestmoore Pl Los Angeles, CA 90065 323-254-9272 http://locationscout.com

[Carter Crain]

Re: [gcmac] Image Reductions without pixelation Marino, I do not think my pictures are pixelated. They look fine for my purposes and load quickly. Why are yours such high quality and so large. It seems a waste of bandwidth and they will load too slowly. Of course you may have different purposes for your pictures than I do for mine. That is why I first asked why he wanted to reduce the size of the file. On 5/16/08 5:40 PM, "Marino Pascal" <weblists@locationscout.com> wrote:   Carter Crain wrote: > Why do you want to reduce the size? > > After trying to understand all the different possibilities, I settled on > mainly reducing the jpeg quality to about 30%. But that's terrible. That's why your pictures are pixelated. >Sometimes I reduced the > size and/or the pixels per inch. My main use was to put pictures on a > website. For the web I use 85% quality and 1024x768 pixels dimensions. My average image is about 150KB without the resource fork which gets lost during uploading. Marino >