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PaintByNumbers

Apps that will reduce a jpg filesize???

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Are there any utilities that will do this? Firing up Photoshop is a pain because it wants all the memory on my computer.

 

I'm looking for a Mac app that would allow me to simply drop an image onto the app and have it ask me what filesize I want it reduced to & what I wanted to name the reduced resolution file.

 

Best I can do right now is to use iPhoto to email a lower res copy to myself, then extract it from the mail attachment folder. But you can't select the precise file size you want.

 

Speaking of iPhoto, it has auto-resizing for many print sizes in inches -- how do inches relate to display resolution sizes in pixels? I hate it when imbedded images turn out to be wider than my screen.

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If you are using iPhoto, you should be able to just export the photo straight to a file (without emailing the file to yourself).

 

I don't know of any apps that allow you to specify the file size and then it figures out the compression quality that is needed. Most people think of things the other way around, particularly since the compression quality percentage (or whatever it is called) really makes a big difference in some pictures.

 

Also, in iPhoto, you can specify the size in pixels for the picture to be exported. As a general rule, graphics displayed online are 72 dpi or 96 dpi. 96 dpi is the most common mac size, if memory serves. 96 dpi = 96 pixels to the inch.

 

Ron

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In iPhoto, I know that I can Duplicate a photo, then Crop and save the cropped photo. But that's not the same as reducing the file size of the entire photo. Emailing allows me to choose 3 resolutions smaller than full size. And I guess its good that the program figures out the required filesize within a range.

 

I'll poke around and see if there's a low res conversion option...

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In iPhoto, I know that I can Duplicate a photo, then Crop and save the cropped photo. But that's not the same as reducing the file size of the entire photo. Emailing allows me to choose 3 resolutions smaller than full size. And I guess its good that the program figures out the required filesize within a range.

 

I'll poke around and see if there's a low res conversion option...

 

If you export the photo (to a file), you get to arbitrarily choose the size in pixels. So, if the original photo is 1600x1200 in pixels, you can specify that the exported photo is only 400 pixels x 300 pixels in size (or about 4in by 3in on screen, assuming that the screen that it is being displayed on is close to 96 dpi in resolution). You can choose 40 pixels by 30 pixels if you really want. iPhoto will take your selected photo and essentially coarsen the image to match the smaller size.

 

Note that the resolution (in terms of pixels per inch) doesn't necessarily change. Applications which provide more control can give you control over the resolution. For example, if I am using an image in (non professional) print, I try to use at least 144 dpi graphics.

 

Ron

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>>>

If you export the photo (to a file), you get to arbitrarily choose the size in pixels.

>>>

 

Aha. I'm good to go.

 

It would be useful for others if various solutions were posted in the FAQs to the two picture-posting forums.

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PBN..

Something to be careful of---

 

JPGs suffer from a thing called lossy compression. Anyway, as a general rule, you are better off manipulating the filesizes before you convert to a jpg format. Lossy compression (just google it if you want an explanation) will cause some pretty ugly artifacts in your photos, if you're not careful.

 

Using photoshop as an example----do all your photo manipulation in .psd format...then when you're done, convert to a jpg. Again, generally speaking, just use the native format of whatever photo software you are using to manipulate the photos---then save the final version in a jpg.

 

Kev

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photobucket has some size reduction abilities. Get a photobucket account, upload your photos, resize them. Then link them to here.

done.

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A lot of the software apps that come with your camera will also allow you to resize your photos rather easily too. I know Nikon Picture Perfect has it as a feature in the 1.5 + versions. This will also allow you, if you choose, to manipulate your pictures in their RAW format and then save as a jpeg or other file type of your choice.

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For the Mac there are two terrific little utilities that will give you better compression results than iPhoto (which is my main beef with the iPhoto resizing).

 

One is Graphic Converter. Depending on the age of your Mac, you may already have this one on your machine. If not it's about $30.

 

Another one is called Imagewell. This one is free. It has a bit of a wonky interface, but it's fast and does just about anything you'd need in the way of basic cropping, resizing, captions, etc. It'll even automatically ftp upload to the web location of your choice, if you elect to provide a location. If not, you can "save as" and manually drag it wherever.

 

kit

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Well this is a Kodak camera and the file format is listed as "JPEG/EXIF 2.2" which must be a proprietary format. But I am using all 4 Mpixels, so there should be some room for loss.

 

Did some test shots the other day, and it seems to have a depth of field of about 3 inches on the Macro setting, which seems good enough.

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Is Graphic Converter still around !? I had that on my Mac Plus circa 1986.

 

Frankt... I don't have a high speed connection, so I posting it thru you isn't the solution; I need to get the file size down on my end.

 

EDITED TO CORRECT TERRIBLE MEMORY

 

Its a 4M pixel camera so the picture size is 2448 x 1632. The LCD (the image sensor in the camera) is 1.8". I think my father went to some trouble to find a camera with that size LCD because it gives a convenient aspect ratio. ???

 

The entire image is 548 Kb in size. Now someone tell me why some of my photos are 2 Mb in size ??? Why aren't the all the same jpeg file size? The camera itself saves them as JPEG/EXIF 2.3 images.

 

This is the closest focus I can get, so the image smallest field of view I can get is about 11" wide x 7 3/4" tall. Well, that's convenient -- I can use an ordinary piece of writing paper to see what will be in-frame. [sECOND EDIT - I think that was the closest I could get and still put 5 figs wide into the frame, IIRC somewhat further than the manual's 6" minimum]

 

On the crop showing all 5 figs I have about a 5" wide x 2 3/4" high image taking up 304 Kb.

 

Each figure is stepped back 2 cm from left to right, and the 4th figure is starting to get out of focus. So I have about a 3" depth of field.

 

***

 

The single figure crop displays as 2 1/4" wide by 3 1/4" tall, at 54 Mb.

 

Since I have an LCD screen I'm sure the quality exceeds what I can display.

 

What is the rule of thumb for "high quality" images; how many bytes per square inch on a good quality CRT monitor?

 

I'll post it on the works in progress under ECW Dragoon

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And thinking along those lines... people never seem to consider that their digital camera can't be better than the resolving power of the lens thats in front of the digital part. I wonder what camera makers consider to be the minimum and maximally useful resolving power for integrated lens digital cameras?

 

I've read that the human eye can resolve about 100 lines per inch. Also one inch at 100 yards. Also 1/1000 radian.

 

Hmmm... the test for resolving power of a lens involves putting a chart with closely spaced lines at a distance of 26 x the focal length of the lens. How the heck do you set the distance with an auto-everything digital camera?

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Is Graphic Converter still around !? I had that on my Mac Plus circa 1986.

Yep, and as it gets updated it retains to capability to edit any image format ever created.

 

Its a 4M pixel camera so the picture size is 2448 x 1632. The LCD (the image sensor in the camera) is 1.8". I think my father went to some trouble to find a camera with that size LCD because it gives a convenient aspect ratio. ???

....

The single figure crop displays as 2 1/4" wide by 3 1/4" tall, at 54 Mb.

 

Since I have an LCD screen I'm sure the quality exceeds what I can display.

 

What is the rule of thumb for "high quality" images; how many bytes per square inch on a good quality CRT monitor?

54 MB? What's the dpi on that? Must be extremely high. Most printers do fine with 150 dpi. For very high quality work I generally save at 300 dpi, but that's for things like posters and banners.

 

Assume 72 dpi and a good percentage of the population who still uses 800x600 on their monitor. The majority of users are viewing between 1024x768 and 1280x1024. If you reduce your image to 800x for display on the web, that will be sufficiently large for anyone. Using between 50-75% compression will get that well below 100k.

 

I usually save large images at 600x around 65% compression when I'm saving jpegs. And I only resave a jpeg once, that is, only once after resizing and retouching. Any more than that and you start getting really ugly artifacts on the image that only worsen on subsequent saves.

 

For archival purposes, I usually save as TIFF and only export as a JPEG when I'm going to drop it on the web. Any editing I do is done on that TIFF file.

 

kit

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Err, that's 54 Kb, not Mega bytes. Geez, when I read that I thought I had uploaded a really huge file to the WIP forum.

 

I've read that if you want to scan a photo, 600 dpi is all you need for best quality. Of course, if you want to enlarge it then you need proportionately more dpi so the enlarged image isn't lower than 600.

 

I thought good CRT monitors resolved a lot better than 72 dpi?

 

72 x 72 would be 5184 = 5.2k dots per square inch.

My single image is about 7.3 square inches; so 7.38 Mb per square inch.

reducing it to only 10% size still leaves 7.38 Kb

-- If that's the right way to figure this out.

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