(Printing) IMAGE RESIZING METHODS

There are various places in Photo Jockey that allow you to select a resizing method. The printing fucntion and the contact sheet function and the image resizing function are just some of the places in Photo Jockey that allow the user to select a resizing method.

PROBLEMS:
As an example....If you want to print an image to the printer, it's possible and very likely that the image you are printing is too small to be sent to the printer. Let's pretend you are using a modern day Canon printer. It's native resolution is 600DPI, that means 600 dots(pixels) per inch. It's internal jet array may be a much higher DPI like 2400 or 4800 in order to dither your colors onto the paper to produce the desired colors. But the actual logical printing surface is 600DPI. Now lets' say you took a photo with a 6MP (mega pixel) camera. The image dimensions would be 3000x2000. Now let's say you print an 8x10. Well, 8 inches at 600DPI would be 4800 dots and 10 inches at 600DPI would be 6000 dots. So an image of 6000x4800 would print perfectly and not need any resizing, but of course your 3000x2000 image is TOO SMALL to fit perfectly, SO what happens is that the 3000x2000 image is INTERNALLY stretched by your printer driver to fit the 6000x4800 area. Remember, not all printer drivers are alike. In fact most of the ones tested seem to not stretch very smartly. They just expand the pixels in the image by a needed factor and you end up with a blocky looking output. Now with the above example, the amount of stretching is only about a 2-to-1 ratio. That's not too bad and can only be noticed if you look at the print-out with a magnifying glass. If the image was a 4MP image then the output would be more noticably jagged (blocky). The more enlarging needed, the more blocky the output would appear.

SOLUTIONS:
In order to solve this problem, you need to supply the printer driver the EXACT SIZED IMAGE so that the driver won't attempt to make the image smaller or larger. By doing this, you eliminate the chance that the driver will stretch or shrink the image. Now, there are several methods of enlarging images to make them appear less jagged and more smooth, while maintaining crisp edges. The following list contains all the stretching methods included with Photo Jockey.

GENERIC: Enlarges the FASTEST and produces the big blocky jagged pixelated effect.

REED: Slowest (Produces the smoothest AND sharpest appearance for photos)

TRIANGLE: Slow Pretty good for most line art.

B-SPLINE: Slow (Produces the smoothest appearance for photos)

LANCZOS: See note below **

MITCHELL: See note below **

BELL: See note below **

HERMITE: See note below **

NOTE ** : These options are available for users that have used them before in other software and want to use those particular methods for some reason or another.

CONCLUSION:
Use the "GENERIC" method for fastest operation and no attempt to smooth.. Use the "REED" method for the best quality on photos. Use "B-SPLINE" for the smoothest effect . LancZos and Mitchell have some good points and some bad points but are generally better than the rest (except for REED). That is why the REED method combines the best features of LancZos and Mitchell to produce the superior REED method. The BELL and HERMITE methods are available only for users that specifically want those methods.

IMPORTANT NOTE:
When printing and selecting an enlarging method, it's possible that your image may be large enough to print nice enough to not waste the time of choosing a high quality enlargement method. This is a good rule of thumb. If you have a 6MP photo, it's okay to print an 8x10 or 4x6 without wasting the time of choosing the "REED" method. If you have a 4MP photo, then printing a 4x6 is fine without wasting time of using a high quality enlargement method.

NOTE: If you CROP a 6MP photo in half, then you must consider using a high quality enlargement method if printing to an 8x10 to get the best results. This is because the cropped image will not keep the 3000x2000 dimensions, if you cropped it in half, then the new image dimensions would be 1500x2000 (which is not even suitable for printing to a 4x6)

HINT: If you are not concerned about maximum quality, then don't select a slow high quality enlargement method (just use GENERIC).

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