Resizing Images

[ShaneS]

I am working on a video slide show of my images using Camtasia studios that I would like to be able to play on my television (Sharp 1920*1080 resolution) but I am having a hard time figuring out how to best resize the images.

I get that the maximum dimensions should be as in the parenthesis above but I have read that the dpi doesn't need to be any higher than 96 and I would like to keep a good balance between file size and image quality. That's the dilemma.

If I change the pixels per inch when I resize the image in Photoshop CS5 it's a pain to get the right number to maximize the dimensions that I want but if I resize to the dimensions my pixels/inch stays high and so does the file size.

I'm sure that there is a very simple solution and I will be slapping myself on the forehead going 'duh!' when you tell me how to do this...but maybe not

[Saorsa]

You might try the free faststone program. I find it's resizing to be simple and fast. It can be found at faststone dot org.

[wobert]

You have CS5- Work with copies, Open Several images, Select the Crop tool- enter 1920px x 1080px and 90ppi in the settings, crop each image and save ( a "Save" action can speed things a bit here.) -done!

[pnodrog]

Make sure the re-size box is ticked.

P.S. I mean resample.

[Colin Southern]

Hi Shane,

The resolution is irrelevant - it can be 10 ppi or 30,000 - doesn't make any difference (it's only used in conjunction with desired physical dimensions, which don't really exist if displaying on a monitor).

What you're wanting is PIXEL DIMENSIONS - not sure what your program offers, but in Photoshop you just select pixels as a unit of measurement and go from there.

Down-sampling to 1920 is easy, but the problem you have is the aspect ratio; if you images are the normal 3:2 aspect ratio and you down-sample them to 1920 then they'll be 1280 high; and if you down-sample them to 1080 high then they'll only be 1620 wide. If you force them to be 1920 x 1080 then your images will be distorted, or if you crop them to those dimensions you'll be losing a part of the image width, so compromises need to be made.

You also need to apply some output sharpening after down-sampling too, or they'll look a touch soft.

I'd be happy to resize them in Photoshop for you if it helps (would only take a minute or so as a batch process).

[yauman]

Ok, forget about dpi - it's only relevant if you are trying to format an image for printing. Your TV is 1920x1080 pixels - so think in pixels. You cannot change the dpi or in this case pixel per inch (PPI) of your TV - it is what it is. So, just format all your images to be 1920pixels x1080 pixels.

One note about color - if you are using a program (like Photoshop or Lightroom) where you can control the color space (color gamut) of your output, use Adobe RGB rather than sRGB (which is usually the default) as your TV have a much wider color gamut than your monitor. sRGB only have about 70% and AdobeRGB has 90% of the NTSC color space.

[Manfred M]

You are overthinking this one. If you have Photoshop; use the image Processor functionality (under <Files> <Scripts>). Put a copy of all the files you want to convert into a folder and set the size to 1920 x 1280 and test to see which image quality (compression level) that works for you.

In my experience, the aspect ratio is maintained and the largest dimension of the image will be either 1920 pixels in width or 1280 pixels in height.

[Colin Southern]

your TV have a much wider color gamut than your monitor.

I'd LOVE to see some data to back that up.

[Colin Southern]

You are overthinking this one. If you have Photoshop; use the image Processor functionality (under <Files> <Scripts>). Put a copy of all the files you want to convert into a folder and set the size to 1920 x 1280 and test to see which image quality (compression level) that works for you.

In my experience, the aspect ratio is maintained and the largest dimension of the image will be either 1920 pixels in width or 1280 pixels in height.

Won't work ... output device is only 1080 high.

[Manfred M]

I'd LOVE to see some data to back that up.

I seem to remember data in this range for the analogue NTSC broadcast standard; but that is now obsolete with HD digital. While the standard may have supported a wider colour space, it took a very expensive high end monitor to actually display colours anywhere close to the theoretical capabilites. There is no technical difference between a modern TV or a computer screen.

[Colin Southern]

I seem to remember data in this range for the analogue NTSC broadcast standard; but that is now obsolete with HD digital. While the standard may have supported a wider colour space, it took a very expensive high end monitor to actually display colours anywhere close to the theoretical capabilites. There is no technical difference between a modern TV or a computer screen.

Yep - that's my understanding of it too. Heck, if it were that easy we'd all just be buying TV to do our editing on in Adobe RGB.

[ShaneS]

I am very comfortable with resizing to the pixel dimensions BUT my files sizes end up plus/minus 3MB and with 30 plus images sound and titles that video slide show will get pretty big fast. My understanding is this is where the compression comes in when you save as a JPEG (starting at 12 or maximum and going down from there) - how much compression is reasonable without sacrificing image quality as displayed on the television?

I am very comfortable resizing to either 1920 or 1080 as the maximum size depending on the orientation of the image and thank everyone who has provided tips so far. Colin I appreciate your offer and do know that I need to sharpen after downsizing for best presentation. I think that I am down to the compression issue but maybe I am oversimplifying things?

[Colin Southern]

I am very comfortable with resizing to the pixel dimensions BUT my files sizes end up plus/minus 3MB and with 30 plus images sound and titles that video slide show will get pretty big fast. My understanding is this is where the compression comes in when you save as a JPEG (starting at 12 or maximum and going down from there) - how much compression is reasonable without sacrificing image quality as displayed on the television?

I am very comfortable resizing to either 1920 or 1080 as the maximum size depending on the orientation of the image and thank everyone who has provided tips so far. Colin I appreciate your offer and do know that I need to sharpen after downsizing for best presentation. I think that I am down to the compression issue but maybe I am oversimplifying things?

Photoshop offers compression on a 1 to 12 scale; generally 10 will be "visually lossless" whilst compressing the size down to somewhere approaching the 1MB mark or less. You could probably go a little lower, although I can't see any particular issue with a 100MB presentation.

[ShaneS]

Thanks Colin - I was a bit impatient so started with level 8 and also switched to 8 bit from 16 before saving and that cut the file size down significantly.

I put the first few images on a thumb drive and plugged it into the TV and they looked really good. It's actually pretty wild to see them on a HDTV as it seems as if you can reach out and touch the items in the images!

I'm off to the races with my 'best of' 2013 slide show now

[Colin Southern]

Thanks Colin - I was a bit impatient so started with level 8 and also switched to 8 bit from 16 before saving and that cut the file size down significantly.

I put the first few images on a thumb drive and plugged it into the TV and they looked really good. It's actually pretty wild to see them on a HDTV as it seems as if you can reach out and touch the items in the images!

I'm off to the races with my 'best of' 2013 slide show now

Hi Shane,

I'm a bit confused - are you sure you're saving them as JPEGs? - a 16 bit JPEG is a pretty rare beast.

Quality 8 will still be very good - I doubt any of the audience would notice the difference between 8 & 10 or even 12.

[ShaneS]

Yes, I am saving them as JPEGs but switching the file from 16 bits to 8 bits prior to saving made the file size as a JPEG smaller.

[Colin Southern]

Yes, I am saving them as JPEGs but switching the file from 16 bits to 8 bits prior to saving made the file size as a JPEG smaller.

Hmmm - that doesn't sound right as for a normal JPEG it needs to convert them to 8 bit anyway.

I'll test tonight.

[dje]

As far as I'm aware, when saving a 16 bit file in CS as a jpeg, it will convert it to 8 bit first anyway. One advantage of converting the image to 8 bit before saving as a jpeg is that it enables the file size preview function in CS (ie gives you an indication of jpeg file size before saving).

Dave

[Colin Southern]

As far as I'm aware, when saving a 16 bit file in CS as a jpeg, it will convert it to 8 bit first anyway. One advantage of converting the image to 8 bit before saving as a jpeg is that it enables the file size preview function in CS (ie gives you an indication of jpeg file size before saving).

Dave

Just did a little test.

- Opened DNG
- Click through to Photoshop
- Change to sRGB
- Save as JPEG - 16 Bit source
- Change to 8 Bit
- Save as JPEG - 8 Bit source

Small difference (some 7000 bytes) - bit surprised, but overall size pretty close. And in this case the 8 Bit is bigger.

Not sure why the difference.

[dje]

I put the first few images on a thumb drive and plugged it into the TV and they looked really good. It's actually pretty wild to see them on a HDTV as it seems as if you can reach out and touch the items in the images!

Shane if you use Camtasia (as indicated in your original post) to produce an actual video file (as distinct from a series of jpegs on a memory stick), the size of the jpeg files shouldn't be an issue. It will be the video codec used to compress the video frames that determines the size of the video file.

Dave