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Thread: Resizing Images With IrfanView

  1. #1
    IV Newbie welder's Avatar
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    Default Resizing Images With IrfanView

    Sorry to bother all,
    A I am a computer illiterate, so you might have answerd the question and I just don't understand. I read a bunch of the posts, I don't understand computerese

    B I am trying to re=size the kb. I belong to a different forum and they have a maximum of 195.3 kb to post a JPG picture / pictures. I figured out how to change pixel size, but My pics have to many KB's. They average around 500 to 600 or so.

    C My camera is a POS kodack, but it's so durable, I can't get rid of it. I tried MS, PICASO, and a few others, One of the guys I know on the other forum told me about this program and this site, and how you could help, Any help would be greatly appreciated. Please PS I have been trying to figure out how to resize for 4 months. Tenacious, huh. Thanx in advance Welder

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    Moderator Sam_Zen's Avatar
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    Well, first of all, try to become less illiterate about these things, don't be passive, but learn.
    One first has to learn about changing gears of a car too, before being able to drive properly.

    Resizing is about changing the pixelsize of a picture. Changing the filesize is another thing.

    If your forum has a restriction about the number of KB's, you better use the 'Save for Web' option.
    There you can set your max of filesize, with a certain compression to monitor the quality that's left.
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    Rest In Peace, Sam!

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    Moderator Bhikkhu Pesala's Avatar
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    First you need to decide how big the file needs to be on the web site. That means the size in pixels. A good average is 600 x 800 for portrait (tall) photos and 1024 x 768 for landscape (wide photos).

    Open the picture in IrfanView and select Resize from the Image menu. In the dialogue box, set the new width to 600 if it is a portrait photo, or 1024 if it is a landscape photo. When you do this the height will change automatically because the box "Preserve aspect ratio" is checked by default.

    In the Resample Filter drop list on the bottom right of the dialogue box, select Lanczos filter (slowest), which gives the best quality. Make sure that the "Resample" radio button is selected, not "Resize." Click on OK to resample your picture to the new dimensions.

    Then you need to save your new picture without overwriting your original. From the File menu, select "Save as" and enter a new file name. In the Save Picture as … dialogue there is a drop list at the bottom that says "Save as type" — select JPG -JPG/JPEG format.

    At top right, another small dialogue will appear where you can set the quality of the compressed image. Move the slider to between about 75 to 90. Lower values will give a smaller file size on disk, but lower image quality. A value of 100 will give the highest quality, but the biggest file size. Reducing the quality only slightly will make the filesize on disk much smaller.

    The other check boxes may change file size too.

    Save original EXIF data keeps the details of the Camera settings used to take the photo. You can clear this check box if this information is not important.

    Likewise with IPTC and JPG comments you can clear those checkboxes unless you need to keep this information — it will all increase the file size on disk.

    The checkbox "Set file size KB (RIOT Plugin)" will override any quality settings that you chose, and resample the image to the filesize you enter in the box, e.g. 195 KBytes.

    That is the "Save for Web" option that Sam-Zen recommended. I suggest not using that option until you have learned the basics of image resizing. You need to learn how quality setting and image dimensions in pixels relate to the filesize on disk. The RIOT plugin will make the decisions for you, which may not be the ones that you want.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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ID:	1337  
    Last edited by Bhikkhu Pesala; 04.04.2009 at 05:45 AM.

  4. #4
    Moderator Bhikkhu Pesala's Avatar
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    Here are some sample images, resized from a big original.

    The first is 1024 wide and saved at a medium high quality setting of 75. It is 77 Kbytes on disk.

    The second is only 640 pixels wide, but saved at a very high quality setting of 99. It is 183 Kbytes on disk — just under your target size of 195.3 Kbytes.

    The second image is bigger on disk (183 Kbytes) but smaller on the screen. It has less detail, but may loook a bit sharper. If your target filesize on disk was 100 Kbytes you could either increase the quality of image 1, or decrease the quality of image 2.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Reclining Buddha 1.jpg 
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ID:	1338   Click image for larger version. 

Name:	Reclining Buddha 2.jpg 
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Size:	181.3 KB 
ID:	1339  
    Last edited by Bhikkhu Pesala; 04.04.2009 at 06:52 AM.

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    Moderator Bhikkhu Pesala's Avatar
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    The third image has not been resized — it is the same dimensions as the original, but it has been saved using the RIOT plugin using the "Set file size" option to keep it below 100 Kbytes. The quality of the image is extremely low, too low to be acceptable. That is why you need to resample your image first.

    The fourth image has been resized, this time to 1280 pixels wide, and saved at a medium high quality setting of 70. I did what RIOT does automatically, by adjusting the quality slider until I got the target filesize on disk that I wanted — 99 Kbytes.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Reclining Buddha 3.jpg 
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ID:	1343   Click image for larger version. 

Name:	Reclining Buddha 4.jpg 
Views:	576 
Size:	98.7 KB 
ID:	1344  
    Last edited by Bhikkhu Pesala; 04.04.2009 at 06:54 AM.

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    IV Newbie welder's Avatar
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    Quote Originally Posted by Sam_Zen View Post
    Well, first of all, try to become less illiterate about these things, don't be passive, but learn.
    One first has to learn about changing gears of a car too, before being able to drive properly.
    .
    Being Passive is a personality trait that I am missing, Being humble, acknowledging my ignorance and seeking help / guidence is totally different. That is why I am here

    Ignorant = lack of knowledge

    Bhikkhu Pesala, Thank you for your guidence, I am going to follow your instructions and will report the results. Thank You for your time and efforts. Welder

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    Nice job, Bhikkhu, and good to make it sticky.

    2 Welder : Ignorance is not exactly the same as lack of knowledge imo, but this is not the place for a filosofical debate.
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    Dear Bhikkhu Pesala,

    I GOT IT!!! TY TY TY.... I transfered all files from Picassa and changed a few, but they all went black and white. I will read some more of these posts to see if I can find the answer. Again Thank You! Welder

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    Quote Originally Posted by welder View Post
    Dear Bhikkhu Pesala,

    I GOT IT!!! TY TY TY.... I transfered all files from Picassa and changed a few, but they all went black and white. I will read some more of these posts to see if I can find the answer. Again Thank You! Welder
    I read some other posts and found out my grey scale was on, Again Thank You, Welder

  10. #10
    Moderator Sam_Zen's Avatar
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    Well, here you are, I wanted to warn for this, but you found out for yourself.. So you're not as ignorant as you said at the start.

    By the way, you called it "..went black and white", but that's not the same as "greyscale".
    Black and white is a bitmap of only 2 colours : every pixel only can have RGB values 0-0-0 or 255-255-255
    Greyscale format contains 256 colours (or less, like 16), with only gradiations of grey, meaning every colour contains an equal value in the RGB setting.
    So the greyscale range is from 0-0-0, 1-1-1, 2-2-2, etc up to 254-254-254, 255-255-255.

    Every bitmap with 256 or less colours has a defined 'palette' of the used values. You can view this property via Image/Palette/Edit palette.
    Last edited by Sam_Zen; 04.04.2009 at 10:31 PM.
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