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10/22/2002 01:12:15 PM · #1 |
I searched through the forum posts about resizing, but could not find the answer to my question. Currently, I am taking pictures on my 3.1 megapixel camera at 2,832 x 2128 pixels, (which equates to 29.5" x 39.3"). I am doing my post processing in PhotoDeluxe, then resizing the file to prints that fit on 8.5 x 11 paper (usually around 7x9). Usually my photos are saved as *.ppd files and are exported to jpeg 640x480 pixel files only when I want to post them online. My question is: If I resize a photo down to fit 8.5x11 paper and save as *.ppd, will I lose image quality if I later take that saved ppd file and resize to a larger print size?
Another question - I just recently changed my camera settings to the largest pixel size setting, and now my printed photos seem very soft. They don't appear as crisp. ????
Linda |
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10/22/2002 03:23:34 PM · #2 |
Originally posted by mcrael:
I searched through the forum posts about resizing, but could not find the answer to my question. Currently, I am taking pictures on my 3.1 megapixel camera at 2,832 x 2128 pixels, (which equates to 29.5" x 39.3"). I am doing my post processing in PhotoDeluxe, then resizing the file to prints that fit on 8.5 x 11 paper (usually around 7x9). Usually my photos are saved as *.ppd files and are exported to jpeg 640x480 pixel files only when I want to post them online. My question is: If I resize a photo down to fit 8.5x11 paper and save as *.ppd, will I lose image quality if I later take that saved ppd file and resize to a larger print size?
Another question - I just recently changed my camera settings to the largest pixel size setting, and now my printed photos seem very soft. They don't appear as crisp. ????
Linda
Actually if you want to print from you 3.1 megapixel size it will only be prudent to print to 8x10.
Take a look at your DPI settings, which for printing should be around 300.
Dimitrii |
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10/22/2002 03:32:48 PM · #3 |
Originally posted by dimitrii:
Actually if you want to print from you 3.1 megapixel size it will only be prudent to print to 8x10.
Take a look at your DPI settings, which for printing should be around 300.
Dimitrii
I am printing all of my prints at 300 dpi. And I acknowledge that with my camera, printing is best quality at 8x10 or smaller. However, this does not answer the question as to whether I will lose image quality if I upsize an image (*.ppd file) that I have previously resized to something smaller.
* This message has been edited by the author on 10/22/2002 3:31:42 PM. |
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10/22/2002 03:48:02 PM · #4 |
I want to answer the image quality question first: If you have a 3.1 Mpixel camera, the actual # of points/pixels will be something like 2048x1536. Any larger output from the camera is bogus: points are added that are not there in the actual image. The only way to add points is to interpolate: find guesses for points (color, brightness) that are between the 'real' pixels. This will lead to the loss of sharpness on the edges. That is what you noticed on the largest pixel number setting.
The dpi setting for printers is a different issue, look in the forum archives.
Last about the first question: any downsizing will lead to information loss if the result is a smaller file. I am not sure about the ppd algorithm, but 'lossy' algorithms like jpeg lead to less and less information the smaller the image. Which makes sense for the smaller image, but don't ask that file to reproduce the original: it can't, since so much information had been lost in the process.
Is this sufficient as answer?
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10/22/2002 03:51:08 PM · #5 |
Always make seperate copies of your originals and only work on your copied versions. These are the only originals you have so you do not want to mess them up. If you downsize an image you throw away pixels which means you are throw away information that you can never recover when you enlarge it again. But if you save your originals you can always go back to them. I use Photoshop but a lot of the tools are the same. When I open up my image the first thing I do is color correct it and adjust the levels, then I save that file at it's original size in a seperate folder I that I name 'Edited'. Then I can crop it, resize it, and print it, and then save an additional copy, for dpcahllenge for example, or just close the file without sving the cropping and size changes. It all depends on what you intend to do with the image. Just make sure you do not save your changes over the original file. This is very important, if you couldn't tell.
T
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10/22/2002 04:58:58 PM · #6 |
| Using Photoshop, can anyone give me a simple, easy way to crop a picture while maintaining a .750 aspect ratio. For instance cropping to meet DPC 640x480 size. Thus far it has been guess work on my part. |
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10/22/2002 05:30:07 PM · #7 |
| Thank you timj351 and johnmk for your replies. They do indeed answer my questions. Regarding the downsizing then upsizing question, your responses were as I suspected. I do keep original unmodified versions of my photos, but not copies of my edits before resizing. CD burning - here I come! |
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10/22/2002 05:36:50 PM · #8 |
Select the Rectangular Marquee Tool from your tool bar then in the Style box at the top info bar select Fixed Aspect Ratio and input 8x6 or 6x8 or 640x480 or 480x640, any numbers that equal the 640x480 ratio will do. Then select the part of the image that you want to crop and then choose Crop rom the Edit menu. Wehn you are finished with that go to to Image Size in the Image menu and under Pixel Dimensions type in 640x480 or 480x640. Then go to Save for Web, choose a size that is below 150kb, name your file so it is seperate from your original and you are done.
T
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10/22/2002 05:37:38 PM · #9 |
Originally posted by johnmk:
I want to answer the image quality question first: If you have a 3.1 Mpixel camera, the actual # of points/pixels will be something like 2048x1536. Any larger output from the camera is bogus: points are added that are not there in the actual image. The only way to add points is to interpolate: find guesses for points (color, brightness) that are between the 'real' pixels. This will lead to the loss of sharpness on the edges. That is what you noticed on the largest pixel number setting.
It is a Fuji, so no matter what setting you choose, it will go trough the interpolated 6mp file first to create a smaller 3mp file from that. The reason is that the Fuji's censor photodiodes are lined diagonally. You cannot get a a valid photo file from that, because the pixels must be in a perfect horizontal/vertical layout.
You want:
XXXX
XXXX
XXXX
The CCD captures:
X_X_X_X
_X_X_X_X
X_X_X_X
(underscores are blank, when I use 'space' it will not show correctly on the forum)
So it interpolates to a
XYXYXYXY
YXYXYXYX
XYXYXYXY
And out of that it computes a
ZZZZ
ZZZZ
ZZZZ
A better graphic presentation is at the bottom of this document.
So the larger file size does give you more information then the 3mp, but is a bit softer and needs more sharpening for printing. I and other people claim that you can use certain resample algorithms to get a better 3mp file then the camera produces.
But when you print a 3mp pic at 300dpi 8x6, the printer driver will interpolate the image up again to a 2400x1800 file. When you use the camera's 6mp file you use more original information than when you feed the printer the ZZZ 3mp file that it has to upsample to a ZAZAZA. With Z being a combination of XY and A an interpolation of Z and ZA is not the same as XY.
When you prepare the 6mp file for printing I think it is best to get a full screen view of your picture so you can see the effects of sharpening. It is a bit experimenting with the settings before you get it right each time.
On the other hand, when the results of the 3mp ZZZ file was satisfactory in the past, use that.
* This message has been edited by the author on 10/22/2002 5:36:16 PM.
* This message has been edited by the author on 10/22/2002 5:38:00 PM. |
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10/22/2002 06:04:13 PM · #10 |
Originally posted by timj351:
...
Great!
Thanks a lot tim!!! |
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10/22/2002 06:07:15 PM · #11 |
Thanks Tim, that will be a great help.
John |
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10/22/2002 06:18:19 PM · #12 |
| Thanks, Azrifel for your additional comment. I was not aware of the intricacies of the Fuji CCD. My reply was more of the general approach. I think you gave a very sound advice. |
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10/22/2002 07:22:32 PM · #13 |
I'm not sure I understand you, Azrifel. I mean I fully understand how the Fuji's Super CCD works but I don't understand what it has to do with anything once the file is saved as a tiff or a jpeg. You have the option of having the camera interpolate the image or not. Fuji's method of interpolating works very well and may be better then Photoshop's method so I would probably use it but once it is saved and you open it up in your editor then it is just an image made up of the same kind of pixels as any other image. At the point you can edit, sharpen it and resize it the same as you do with any other image.
T
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10/23/2002 03:36:34 AM · #14 |
Originally posted by timj351:
I'm not sure I understand you, Azrifel. I mean I fully understand how the Fuji's Super CCD works but I don't understand what it has to do with anything once the file is saved as a tiff or a jpeg. You have the option of having the camera interpolate the image or not.
No matter what file size setting you use on a superccd, it has to go trough the maximum, interpolated, size first. When you choose to use the 3mp option, you have already lost some information for large prints. The 3mp is good for 300dpi prints up to 6.83x5.12inch.
When you want to print larger than that at 300dpi, the 3mp file has to be interpolated up again (manually, program or printer driver). At that moment you are interpolating already interpolated pixels (and I don't even wan't to go into the bayer interpolation that went on before the first interpolation to 6mp).
But what I want to say is: you have no option.
The 3mp file is always a downsampled version of a 6mp interpolated ccd capture. And it is not hard to beat that downsampling quality with an editor, preferably using something like Lanczos3 algorithm.
Only the 1mp ISO800/1600 setting is somewhat real, altough it is made up from coupled photodiodes.
The in camera downsample to 3mp is fine for small prints, but when you want to do a big print it is better to use and work on the 6mp original.
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10/23/2002 05:05:35 AM · #15 |
well I just read through the review on the Fujifilm FinePix S602 and I did not read anywhere where it said that even with the 3 megapixel resolution the camera interpolates up to 6 and then back down to 3 megapixels. It could have been there and I just missed it but it is really beside my point. The review clearly stated that the 3 megapixel output was very good all the same. So my point is regardless of how the final image is achieved and whether you use the 3 or 6 megapixel setting, if it looks good then it looks good, period, and so it should have plenty of image detail to enlarge to an 8x10 or larger and still look very good. I just can't see that any additional, fancy processing should be necessary to enlarge it. Maybe Genuine Fractals, but that is used with other types of images as well.
T
* This message has been edited by the author on 10/23/2002 5:04:41 AM.
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10/23/2002 06:36:11 AM · #16 |
Originally posted by timj351:
The review clearly stated that the 3 megapixel output was very good all the same. So my point is regardless of how the final image is achieved and whether you use the 3 or 6 megapixel setting, if it looks good then it looks good, period, and so it should have plenty of image detail to enlarge to an 8x10 or larger and still look very good.
My first comment was to explain why a Fuji interpolated 6mp file from a 3mp SuperCCD is something else as a 6mp interpolated file from a regular ccd. It needs to go trough the proces, or else it cannot create a file with a horizontal x vertical pixel layout. Jpeg and Tiff don't work with diagonal pixel layouts. It was just additional info for the one I reacted to.
And at the end I did say that when you are happy with the 3mp's prints there is no reason to switch to 6mp if it causes troubles. But my opinion is that you can get a tiny bit better quality from the 6mp, but apparently that is not always easy to achieve.
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