Process for Web

Discussion in 'General Technical Discussion' started by triangular, Dec 1, 2005.

  1. What is the way you do this that maintains image quality and keeps a small file size? I guess I'm used to working with less pixels, and now I'm not sure about the math. I'd like to keep my jpg's between 50-100K in file size, 600 pixels wide on the verticals and 800 pixels wide on the horizontal images, at 72ppi. If I use Photoshop's Image Size panel, that means a first pass to resize the hoz/ver resolution with bicubic sharper, then a 2nd pass to lower ppi to 72 with image scaling turned off. Then save as JPG between levels 4-6. Is this a good method? What is better? Thanks.

    Christian
     
  2. I do just this exact thing all the time and here's how I do it with Photoshop CS.

    1. Go to Image Size and be sure Resample Image/Bicubic Sharper is checked. In one step change the dpi to 72 then change the pixel dimension to what you need for that image. Click Okay.

    2. Go to Image/Mode/Convert to Profile sRGB.

    3. Go to Hue Saturation and bump saturation by 5%

    (I have steps 2 and 3 assigned as an Action)

    4. Do a Save for Web and slide the Quality slider around until you get the k-size you want. It varies, but keeping an "average" 600 long-dimension pixel .jpeg under 100k will usually put you in the quality range of 50-70 percent. Images with a lot of detail like pictures of trees will require more compression than say pictures with a lot of areas of flat colored panels.

    An "average" 800 x 600 pixel image under 100k is going to be severely compressed

    Good luck

    Woody
     
  3. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    I don't bother with the DPI - this only affects the image if you are going to print it. Plus using bicubic sharper sometimes results in an over-sharpened image, which also increases it's file size dramatically, especially if you have a lot of sand or grass in the photo (as the edges of every grain/blade are enhanced.)

    I use just plain bicubic, then make a duplicate layer, use smart sharpen on the layer, then erase where it doesn't need sharpened. Flatten the image and Save for Web if I'm trying to get the smallest file, cause Save As... saves the exif, which adds about 20K to the file size.

    If you don't have CS2, and thus no smart sharpen, make the layer a 'darken' layer and use unsharp mask with a small radius (0.2) and large amount (200-400) for a similar effect.
     
  4. I do have CS2 but I don't usually use Save For Web because it's so much a longer process than just making an action to Save As JPG. But one thing I didn't know was that Save As Web cuts the EXIF data. Does it still retain the Metadata (such as copyright, email, etc.)?

    The reason I want to set web images to 72ppi is exactly for the print reason. I think 1st it should cut the file size because the image is then using fewer pixels, but it also limits the printed quality if someone else were to download and print that image. Is my thinking correct about this?

    Christian
     
  5. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    No. If you notice that when you change the ppi number to 72, the pixel width and height do not change. If you want to make a photo unprintable, keep it small (400-480 pixels maximum dimension) and use a lot of jpeg compression. That way, if they try upsizing it'll get ugly from the jpeg artifacting. These 960X532 at max quality pictures, that we often post here, can be upsized and printed at 4 inches by 6 inches with pretty good quality.

    Oh, I am unsure if Save for Web strips copyright or not.
     
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