Thinking of posting pictures?

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oscar g
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Re: Thinking of posting pictures?

Postby oscar g » Mon Dec 26, 2016 5:02 pm

Changing a fixed handle to a recessed position on my mill.
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Folding Mill Handle--12-26-16.jpg

Atkinson_Railroad
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Re: Thinking of posting pictures?

Postby Atkinson_Railroad » Sun Jan 22, 2017 7:47 am

Experimenting with various photo sizes I’ve discovered that when opening a photo in the MS Paint program
and placing text on the photo, it reduces the KB file size of the photo yet the pixel count remains the same.

PROPERTIES OF PHOTO WITHOUT TEXT

Width………...1000 pixels
Height………..720 pixels
File size………396 KB

Resolution……300 dpi
Bit depth……...24


PROPERTIES OF SAME PHOTO WITH TEXT

Width…………1000 pixels
Height………...720 pixels
File size……….104 KB

Resolution…….96 dpi
Bit depth………24

Testing to see how the two photos load on the site, and what differences if any can be observed.
Attachments
scan0012 720.jpg
scan0012 720 P.jpg
TEST THREE.jpg
Dimensions 1000 X 765

Atkinson_Railroad
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Re: Thinking of posting pictures?

Postby Atkinson_Railroad » Mon Jan 23, 2017 6:44 am

TEST 550 x 720
Attachments
TEST FIVE.jpg
Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window.

Testing capacity of FILE COMMENT window.Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window. Testing capacity of FILE COMMENT window.

space TEST

space
Testing capacity of FILE COMMENT window.

0123456789 0123456789 0123456789 0123456789 TEST

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ctwo
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Re: Thinking of posting pictures?

Postby ctwo » Mon Jan 23, 2017 6:21 pm

jpg is a compressed format and you generally have controls to control how much compression is desired. Resolution (dpi) is meaningless in digital imagery because a pixel will use a pixel on your display device, and not all display devices (and their pixels) are the same size. dpi will affect print resolution and/or print size.

1000 x 720 = 720,000 pixels of 24 bits depth = 2.16 MB uncompressed. I can see compression artifacts and image loss in the second image that correlates with highly increased compression.

As a jpg file, I can get it's size down to ~34KB, but you can start to see the image loss.
Attachments
scan0012-720.jpg
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Atkinson_Railroad
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Re: Thinking of posting pictures?

Postby Atkinson_Railroad » Tue Jan 24, 2017 1:47 pm

Your description of dpi / pixels related to screen and print resolution is very helpful.
Thanks for your reply ctwo.

John

Doug4d3s
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Re: Thinking of posting pictures?

Postby Doug4d3s » Tue Jul 25, 2017 11:48 am

Atkinson_Railroad wrote:Experimenting with various photo sizes I’ve discovered that when opening a photo in the MS Paint program
and placing text on the photo, it reduces the KB file size of the photo yet the pixel count remains the same...

That's not a feature particular to MS Paint.
Because of the type of "lossy" compression that jpg images use, every time you edit and save them they lose more visual data--and become smaller in file size. And the compression artifacts (the "tiling") increases, too.

If you saved it as a 24-bit PNG it wouldn't lose data that you didn't alter yourself, but then,,, it wouldn't end up nearly as small as a jpg would either.

-------

Speaking of dial-up, is anyone (in the USA) still on it?
Some months back I was informed that AT&T was no longer leasing phone lines at data rates (which was lower than for voice transmission).
Because of this, all the internet service providers still offering dial-up accounts had to shut them down. I am in the St Louis (midwest) region...

Also we note: a friend who is a cable guy (Comcast/Charter) says that all of the people who do any kind of line work are now being trained for working with optical fiber. The current US-telecom-industry word is that wire phone lines (and cable-TV lines too!) are on the way out. Fiber-optic has gotten so cheap that there's no reason not to use it.
.........
It's not going to be real soon, as there's some legal requirements of US phone service that must be changed to allow doing it.
(some of the technical requirements that current phone company service must meet are only applicable to an analog telephone on a wired connection; there is no allowance for a digital-based service at all)
It is coming, though.

Harold_V
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Re: Thinking of posting pictures?

Postby Harold_V » Tue Jul 25, 2017 3:46 pm

Doug4d3s wrote: Fiber-optic has gotten so cheap that there's no reason not to use it.

Perhaps you're not familiar with TDS?

We live in a sparsely populated county, and they're the soul provider where we live. Sure, they have fiber around the perimeter of their area of service, but lines are still copper, and they're not in any hurry to convert to fiber. I've had a DSL connection for years, and have "enjoyed" the experience of watching the supposed 5mbps service decrease to the point where it is commonly well under 1 mbps. Complaints to them fall on deaf ears. They don't care, and they have good reason to assume that posture, as the cost for our slow service is greater than the higher speed service offered to those with a faster connection.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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BigDumbDinosaur
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Thinking of posting pictures?

Postby BigDumbDinosaur » Wed Jul 26, 2017 1:10 am

I convert a lot of images to GIF. GIF uses the LZW lossless compression algorithm, but only carries eight bits color information. In most cases, the resulting 256 color palette is more than sufficient. So I get an image that renders at the same resolution as the original but with a smaller file size, since less color info is carried along.

Incidentally, the chip in the below image is approximately 7/8 inch in length, so you can get an idea just how close that close-up was and how well the GIF carries the image data.

pcb_sram_close.gif
Hi-Res Close- Up in GIF
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BClemens
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Re: Thinking of posting pictures?

Postby BClemens » Fri Sep 01, 2017 6:22 am

What is a good file format for drawings?

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BigDumbDinosaur
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Re: Thinking of posting pictures?

Postby BigDumbDinosaur » Fri Sep 01, 2017 12:13 pm

BClemens wrote:What is a good file format for drawings?

I recommend GIF, especially if the drawings are black and white. GIF carries less color information than the other formats but uses a lossless compression algorithm, unlike JPEG. For example, the below image is less than 17 KB in size but has the exact same resolution as the original drawing from which the image was derived. Its equivalent in JPEG would be at least three times as large, yet actually convey less resolution.
clock_gen_2phase.GIF
Black & White Drawing in GIF

GIF carries eight bits of color information, which limits the palette to 256 colors. In many cases, that is actually sufficient to produce an acceptable color image, especially of inanimate objects. Many of the photos I posted in my F7 build log are GIFs. The below image is a GIF but looks almost exactly like the actual object, at least to my eyes.
pocv1_1_02_reduced.gif
Example Color GIF
Science makes it known. Engineering makes it work.

BClemens
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Re: Thinking of posting pictures?

Postby BClemens » Thu Sep 07, 2017 12:48 pm

BDD,
I noticed that 'photobucket.com' has changed their approach with helping post pictures....but why do we need a photo host anyhow? This site along with many others has the capability to upload photos directly from a hard drive - or is there something wrong with doing it that way?
Thanks,
BC

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BigDumbDinosaur
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Re: Thinking of posting pictures?

Postby BigDumbDinosaur » Thu Sep 07, 2017 10:21 pm

BClemens wrote:I noticed that 'photobucket.com' has changed their approach with helping post pictures....but why do we need a photo host anyhow?

I see no reason to link to sites such as photobucket when posting here. Attaching a photo to a Chaski post not only is convenient it assures that the photo will be there every time someone views the post. Linking to another site for a picture means the person reading the post has to wait while the other site responds to the read request. If the site fails to respond or if the file containing the picture somehow gets deleted the person reading the post sees nothing.

Also, many of these photo hosting sites throw in some advertising for good measure. I don't know about you, but I'm not in the habit of offering free advertising to others, and I certainly don't want to see someone's ads overwriting part of my picture.
Science makes it known. Engineering makes it work.


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