Question: What size (width and height) of the image to vertical upload (blue top) in SpectralWorkbench?

asasergio is asking a question about spectral-workbench
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by asasergio | January 24, 2016 01:12 | #12607

I need to know if an image filed in the smartphone (Samsung Galaxy S3), to be upload in SpectralWorkbench, need to have standard size (height and width), or sides in a particular proportion, and what would it be.

I resized (edit) the image, captured with my smartphone, so that it looks like the example "Vertical, blue on top" (landscape) of the upload SpectralWorkbench page and as a result, after the upload, the image can not be calibrated.


Test 1 Upload image: as it was captured by smartphone


...result in SpectralWorkbench, unfit for calibration:


Test 2 Upload image: after resize height and width


...result in SpectralWorkbench, observed B2 and G2 values not compatible:


Test 3 Upload image: after resize height and width, second try


...result in SpectralWorkbench, observed B2 and G2 values not compatible:


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Hi, thanks for reporting. For the first and second, did you have the "vertical" checkbox checked? Perhaps for one but not the other?

For the calibration itself, you need to choose a cross section that intersects the spectrum at your desired height. Then there will be a marker for cross section on the image. As it is now, it's sampling the top row of pixels. I'm going to create a feature request that for vertical images, it uses the middle row of pixels. That may work better for folks using a foldable spectrometer:

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"vertical" checkbox (of SpectralWorkbench upload page) checked in the three tests.

Now, rotating and cutting the test 1 image, I did two uploads with:


  • Test 4


... result


  • Test 5


... result


...see You that the result of B2 and G2 should be close to 435.83nm and 546.07nm, but these are my results:

Test 4: B2 = 1198.37nm and G2 = 1599.49nm

Test 5: B2 = 113.13nm and G2 = 514.11nm

I think I can get two conclusions, that is, I have two variables influencing my results:

The score remains the same regardless of the length of the image. Maybe the DVD I used is not appropriate for the spectral kit 3.

The length of the image modifies the wavelength. I'm in trouble with the dimensions.

I bought "Diffraction Gratings 1000 line/mm" but not yet received.

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This is an issue with the instructions highlighted by @stevie -- your spectra are well calibrated and the 435/546 #s refer to the nanometer positions the lines should have after you calibrate. We're working on a better wording there -- maybe:

"Before calibrating, the horizontal axis lists the pixel position along the spectrum. After you calibrate and save, the B2 and G2 lines should appear at 435 and 546 nanometers, respectively, if you're aligned well with the reference spectrum."

What do you think?

Another note -- you should upload without cropping because the calibration needs to be at the same image size and proportions as any later spectrum, so that the calibration will be transferable.

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