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Picture reducing.

Discussion in 'Digital Photography & Imaging' started by Del Monte, Oct 17, 2003.

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  1. Del Monte

    Del Monte Thread Starter

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    I have been using a Kodak DC4800 digital camera for a little more than 2 years now. The biggest problem I have is reducing the picture size and maintainig the focus or picture sharpness. I'm using the Corel Photo House software for my picture customizing. With the picture resolution on the digital camera set at the highest level (3.1 meg) the image properties are 20"x30", in a .jpeg file. I like the shrink the pictures to a 4"x6" size for emailing and uploading to web sites, but doing this causes the photo to get blurry, and the sharpness is gone. Is a there a way to reduce the picture size and keep the sharpness? Do I need better software for this duty? Thanks for any help.
     
  2. hewee

    hewee

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    You should be ok resizing the image for email and the web. Best to not compress them if they are. jpg. You can save them as .PNG also they are about the same file size as .jpg but a better format.

    Also you can get the "Free DCE (Digital Camera Enhancer)"

    http://www.mediachance.com/digicam/index.html

    Other tools on this page are also free.
     
  3. Del Monte

    Del Monte Thread Starter

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    Thanks hewee.

    Tell me though, if my camera is preset to save my pictures as .jpeg files, how do I change them to .png file?

    Del
     
  4. SweetChick

    SweetChick

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    I use Paint Shop Pro 7 for my digital pictures, it does a very good job of reducing picture size, it lets you choose the size and compression level, if I choose the lowest compression the picture still looks like the original, just smaller in size but not much smaller in bytes, but if I choose a much higher compression level the picture will start to lose some sharpness but be much smaller in bytes.
     
  5. slipe

    slipe

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    There are various methods of resizing. A simple resize is fast but it gives poor quality. Photoshop uses bicubic resampling as its best method and Irfanview and ohers use a Lanczos resample filter as their best quality resample. Either are very good. There is a program called Genuine Fractals that some people feel does an even better job, but you are buying a separate program just for the purpose of resizing. I often use a technique called stair interpolation in Photoshop which gives results similar to Genuine Fractals. You need something with at least Lanczos or bicubic though. The freeware Irfanview offers several resize filters including Lanczos and I recommend it highly for resizing: www.irfanview.com

    At best quality the image size from your camera is 2160 X 1440 pixels. Print size has nothing to do with the image size. The camera arbitrarily assigns a print size which then gives a resolution if you would print at that size. It is simply a code embedded in the image file to tell the printer what size to print. You should set the software to not resample when you set the print size so you don’t lose pixels. So if you set the software to print a 4 X 6 you should have over 300PPI for the resolution. That represents how tightly packed your 2160 X 1440 pixels are if you put them on a 4 X 6 inch of paper.

    E-mail recipients and web viewers see the image in pixels. If they have the screen resolution set for 600 X 800 and you send or post an image that is 400 pixels wide it will stretch halfway across their screen. If they have the resolution set at 1200 X 1600 the 400 pixel wide image will stretch only a quarter of the way across their screen. Most people display at least 600 X 800 and it is a safe bet to size the height of your images to 400.

    When you save as JPG there are quality choices. The higher the quality the larger the file. JPG artifacts multiply – sort of like the old rule of not making copies of copies of tapes. If you work with a file in an image editor save it as a TIF, PNG or other uncompressed file type to avoid enhancing the JPG artifacts. There is nothing you can do to avoid getting the image from the camera as a JPG and you should always save that original JPG from the camera. But once you take the image into an editor do not resave it as a JPG. You re-compress it and multiply the artifacts from the camera compressing it. You would probably save downsized images for e-mail as JPG, which is fine as long as you don’t overwrite the original image.

    I would use Irfanview for resizing if I were you. It has an excellent Lanczos filter and doesn’t confuse the image and print size. It doesn’t involve you with the print size unless you print something – then it asks for sizes etc.
     
  6. hewee

    hewee

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    This from the help file in Photo-brush.

    Interpolation: Photo-Brush has several types of interpolation. Generally, for images, the Bi-Linear 2 pass, Bi-Linear or Bicubic should produce the best results. However, in some special cases (like resizing line art or text), a different filter may give you better quality.

    Bi-linear 2 pass is great for shrinking images and Lanczos 3 or Bicubic should be better for enlarging. You probably won't see much difference with the other filters if you use them with normal photographs and the resizing factors are not very big..

    If you need to create a very small thumbnail from your image (resizng down by a great deal, then Bi-linear 2 pass or Lanczos 3 will create the best results - smooth image without jagged edges.
    Bi-Linear 2 Pass (Photo-Brush only) is a special interpolation filter designed for sizing down digital photography. It produces very smooth image with no jagged edges. Result image is also usually softer than with other interpolation. As a next step after Bi-Linear 2 Pass you should apply a sharpening (Unsharp Mask). With this setup you can control the overall feel of the image much more that with other interpolation.

    You will see the effect more obvious when you resizing big image into much smaller, thumbnail size. On the image above we resized original 3 MegaPixel digital image to 150x112 pixels. You see the result thumbnail and a zoom into it. The Bi-Linear (or Bi-Cubic) will produce visible jagged edges. The Lanczos 3 will produce much more pleasant image which is already sharp and without many disturbing artifacts. Bi-Linnear 2 Pass will produce even more smoother image, just ready to apply some sharpening.

    We designed the Bi-Linear 2 Pass to be the best Interpolation filter for most of your digital images. Of course you have a great choice of Interpolation filter so you can use whichever produces best images for you.

    If you would like to enlarge small image into much bigger size, then Lanczos 3 would be the best choice.

    The size preview window shows the relationship between the original size (red) and the new size (blue).
    Tip: You can change the size by clicking and dragging your mouse inside the preview window as well.
    Resample Image

    Image - Resample

    Warning: If you are not quite sure you need to resample the image, then you most likely don’t need to. Resampling can create unnecessarily large images which are difficult to edit.
    In any cases use Resampling as one of your last step; do all your image tweaking before resampling.

    Resample takes a different approach to resizing. In Resizing you are basically specifying the image size in pixels (which is most important information).
    In Resampling you have to specify the desired DPI and also desired size in inches. This is obviously for cases when you need the image for a future printing project. Setting up DPI or the inch size for screen images makes little or no sense - in that case you should use Resizing.

    As it is in the image above we specified DPI 300 while output should be in desired 6*4.5 inch. The dialog also shows the Result in pixel size, in our case 1800*1350 which is enlargement from original 1600*1200.

    It is important that you need to set both values DPI and size.
    The tool can suggest best interpolation for your resizing (- which is Lanczos 3 for enlarging), but you can choose your own.

    If your result will be JPG then the DPI Resolution Flag of the JPG will be also set to this value.

    Important:

    If the exact DPI/size is not an absolute requirement (for example by your printing house), then you should probably avoid any Resampling. All printers should be able to resize the image into desired size. However, you may feel that Photo-Brush interpolation does a better job than the printers. In this case you may try to use Resampling and compare the results.

    If you only need to set DPI of the image, but you don't care about the size, don't use Resample either. Simply save as JPG and set DPI resolution flag on the JPG quality settings.

    These are all I have to pick from but have not used all of them . Use the Bi-linear 2 pass as it was the default and never played around with using the others.

    [​IMG]
     

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  7. Del Monte

    Del Monte Thread Starter

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    Whoops! Boy did I step into a whole new field. I have to do some downloading and alot of reading. Please keep the information coming. I will be coming back for more answers. Right now I'm a bit lost, but I'll figure it out.


    Del
     
  8. wanabe_buck

    wanabe_buck Guest

    In the short run...if you use Irfanview or anything that has the lanczos or bicubic filter...as slipe has pointed out...you should be able to resize for the web or email without trouble or tremendous loss of quality...if you are something is not working correct

    buck
     
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